Exhibit 4.1

DESCRIPTION OF UNITED STATES LIME & MINERALS, INC.’S

SECURITIES REGISTERED UNDER SECTION 12 OF THE

SECURITIES EXCHANGE ACT OF 1934, AS AMENDED

General

United States Lime & Minerals, Inc. (the “Company,” “we,” or “our”) is incorporated in the State of Texas. The rights of our shareholders are generally covered by Texas law and our articles of incorporation and bylaws (each as amended and restated and in effect on the date hereof). The terms of our common stock are therefore subject to Texas law, including the Texas Business Organizations Code (the “TBOC”), and the common and constitutional law of Texas.

This exhibit describes the general terms of our common stock. This description is a summary and does not purport to be complete. Our articles of incorporation and bylaws are incorporated by reference as exhibits to the Annual Report on Form 10-K of which this exhibit is a part, and amendments or restatements of each will be filed with the Securities and Exchange Commission (the “SEC”) in future periodic or current reports in accordance with the rules of the SEC. You are encouraged to read these documents.

For more detailed information about the rights of holders of our common stock, you should refer to our articles of incorporation and bylaws and the applicable provisions of Texas law, including the TBOC.

Authorized Capital Stock

We are authorized to issue 30,000,000 shares of common stock, $0.10 par value, and 500,000 shares of preferred stock, $5.00 par value.

Common Stock

Voting Rights

Holders of our common stock are entitled to one vote per share in the election of directors and on all other matters submitted to a vote of shareholders. No shareholder has the right of cumulative voting.

With respect to any matter other than the election of directors or a matter for which the affirmative vote of the holders of a specified portion of the shares of our common stock entitled to vote is required by Texas law or our articles of incorporation, the act of the shareholders shall be the affirmative vote of the holders of a majority of the shares entitled to vote on, and voted for or against, the matter at a meeting of shareholders at which a quorum is present. Directors shall be elected by a plurality of the votes cast by the holders of shares entitled to vote in the election of directors at a meeting of shareholders at which a quorum is present. We do not have a classified board of directors. Our directors are elected for one-year terms.

Dividend Rights

Holders of our common stock are entitled to dividends when, as and if declared by our Board of Directors out of funds legally available therefor.

Liquidation Rights

If we liquidate, a holder of common stock will be entitled to share ratably with the other shareholders in the distribution of all assets that we have left after we pay all of our liabilities and make any necessary distributions to holders of our preferred stock.

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Other

Our common stock has no preemptive or conversion rights and is not entitled to the benefits of any redemption or sinking fund provision. The outstanding shares of our common stock are fully paid and non-assessable.

Preferred Stock

The Company may issue shares of preferred stock from time to time upon the approval of our Board of Directors in one or more series without further stockholder approval. The Board of Directors may designate the number of shares to be issued in such series and the rights, preferences, privileges and restrictions granted to, or imposed on, the holders of such shares. If issued, such shares of preferred stock could have dividends and liquidation preferences over our shares of common stock, and may otherwise affect the rights of the holders of the common stock. The rights of the holders of our common stock will, therefore, generally be subject to the rights of the holders of any existing outstanding shares of preferred stock with respect to dividends, liquidation preferences and other matters. As of the date hereof, we have no outstanding shares of preferred stock.

Certain Business Combination Restrictions in Texas Law

Section 21.606 of the TBOC restricts certain business combinations between us and an affiliated shareholder (beneficial ownership of 20% or more of the voting power of our stock entitled to vote for directors) for three years after the shareholder becomes an affiliated shareholder. The restrictions do not apply if our Board of Directors approved the transaction that caused the shareholder to become an affiliated shareholder, or if the business combination is approved by the affirmative vote of two-thirds of our voting stock that is not beneficially owned by the affiliated shareholder at a meeting of shareholders called for that purpose within six months after the affiliated shareholder’s acquiring the shares. Although we may elect to exclude ourselves from the restrictions imposed by Section 21.606, our articles of incorporation does not do so.

Certain Provisions of Our Articles of Incorporation and Bylaws

Some provisions of our articles of incorporation and bylaws could make the acquisition of control of the Company and/or the removal of our existing management more difficult, including those that provide as follows:

These provisions may be expected to discourage coercive takeover practices and inadequate takeover bids. They may also encourage persons seeking to acquire control of the Company to first negotiate with our Board of Directors. We believe that the benefits of our increased protection give us the potential ability to negotiate with the proponent of an unfriendly or unsolicited proposal to acquire or restructure us, and that these benefits outweigh the disadvantages of discouraging the proposals. Negotiating with the proponent could result in an improvement of the terms of the proposal.

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Stock Exchange Listing

Our common stock is traded on the Nasdaq Stock Market under the symbol “USLM.”

Transfer Agent and Registrar

Our transfer agent and registrar is Computershare Investor Services, P.O. Box 30170, College Station, TX 77842.

Exhibit 21.1

SUBSIDIARIES OF THE COMPANY

Arkansas Lime Company, an Arkansas Corporation

ACT Holdings, Inc., a Texas Corporation

ART Quarry TRS LLC (DBA Carthage Crushed Limestone), a Delaware LLC

Colorado Lime Company, a Colorado Corporation

Mill Creek Dolomite, LLC, an Oklahoma Corporation

Texas Lime Company, a Texas Corporation

U.S. Lime Company, a Texas Corporation

U.S. Lime Company—Shreveport, a Louisiana Corporation

U.S. Lime Company—St. Clair, a Delaware Corporation

U.S. Lime Company—Transportation, a Texas Corporation

U.S. Lime Company—O & G, LLC, a Texas LLC

Exhibit 23.1

CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

We have issued our reports dated March 10, 2022 with respect to the consolidated financial statements and internal control over financial reporting included in the Annual Report of United States Lime & Minerals, Inc. on Form 10-K for the year ended December 31, 2021.  We consent to the incorporation by reference of said reports in the Registration Statements of United States Lime & Minerals, Inc. on Forms S-8 (File No. 333-236817 and File No. 333-196697).

/s/ GRANT THORNTON LLP 

Dallas, Texas

March 10, 2022

Exhibit 23.2

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CONSENT OF QUALIFIED PERSON

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SYB Group, LLC (“SYB”) in connection with the filing of the United States Lime & Minerals, Inc. Annual Report on Form 10-K (the “Form 10-K”), consent to:

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SYB is responsible for authoring, and this consent pertains to, the Technical Report Summaries. SYB certifies that it has read the Form 10-K and that it fairly represents the information in the sections of the Technical Report Summaries for which SYB is responsible.

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SYB Group, LLC

/s/ Keith Vickers

President

March 10, 2022

EXHIBIT 31.1

RULE 13a-14(a)/15d-14(a) CERTIFICATION BY THE CHIEF EXECUTIVE OFFICER

I, Timothy W. Byrne, certify that:

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EXHIBIT 31.2

RULE 13a-14(a)/15d-14(a) CERTIFICATION BY THE CHIEF FINANCIAL OFFICER

I, Michael L. Wiedemer, certify that:

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EXHIBIT 32.1

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SECTION 1350 CERTIFICATION BY THE CHIEF EXECUTIVE OFFICER

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I, Timothy W. Byrne, Chief Executive Officer of United States Lime & Minerals, Inc. (the “Company”), hereby certify that, to my knowledge:

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EXHIBIT 32.2

SECTION 1350 CERTIFICATION BY THE CHIEF FINANCIAL OFFICER

I, Michael L. Wiedemer, Chief Financial Officer of United States Lime & Minerals, Inc. (the “Company”), hereby certify that to my knowledge:

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EXHIBIT 95.1

MINE SAFETY DISCLOSURES

The following disclosures are provided pursuant to Section 1503(a) of the Dodd-Frank Wall Street Reform and Consumer Protection Act and Item 104 of SEC Regulation S-K, which requires certain disclosures by companies required to file periodic reports under the Securities Exchange Act of 1934, as amended, that operate mines regulated under the Federal Mine Safety and Health Act of 1977 (the “Mine Act”).

The Mine Act has been construed as authorizing MSHA to issue citations and orders pursuant to the legal doctrine of strict liability, or liability without fault. If, in the opinion of an MSHA inspector, a condition that violates the Mine Act or regulations promulgated pursuant to it exists, then a citation or order will be issued regardless of whether the operator had any knowledge of, or fault in, the existence of that condition. Many of the Mine Act standards include one or more subjective elements, so that issuance of a citation or order often depends on the opinions or experience of the MSHA inspector involved, and the frequency and severity of citations and orders will vary from inspector to inspector.

Whenever MSHA believes that a violation of the Mine Act, any health or safety standard, or any regulation has occurred, it may issue a citation or order which describes the violation and fixes a time within which the operator must abate the violation. In some situations, such as when MSHA believes that conditions pose a hazard to miners, MSHA may issue an order requiring cessation of operations, or removal of miners from the area of the mine, affected by the condition until the hazards are corrected. Whenever MSHA issues a citation or order, it has authority to propose a civil penalty or fine, as a result of the violation, that the operator is ordered to pay.

The table that follows reflects citations, orders, violations and proposed assessments issued to the Company by MSHA during the year ended December 31, 2021 and any pending legal actions as of December 31, 2021. Due to timing and other factors, the data may not agree with the mine data retrieval system maintained by MSHA. The proposed assessments for the year ended December 31, 2021 were taken from the MSHA system as of March 9, 2022.

Additional information follows about MSHA references used in the table:

Citations and orders can be contested before the Federal Mine Safety and Health Review Commission (the “Commission”), and as part of that process, are often reduced in severity and amount, and are sometimes dismissed. The Commission is an independent adjudicative agency that provides administrative trial and appellate review of legal disputes arising under the Mine Act. These cases may involve, among other questions, challenges by operators to citations, orders and penalties they have received from MSHA, or complaints of discrimination by miners under section 105 of the Mine Act.

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Year ended December 31, 2021

Pattern or Potential Pattern of Violations. During the year ended December 31, 2021, none of the mines operated by the Company received written notice from MSHA of either (a) a pattern of violations of mandatory health or safety standards that are of such nature as could have significantly and substantially contributed to mine health or safety hazards under section 104(e) of the Mine Act or (b) the potential to have such a pattern.

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Exhibit 96.1

Technical Report Summary on

Texas Lime Company Limestone Operation

Johnson County, Texas, USA

Prepared for:

United States Lime and Minerals, Inc.

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SK-1300 Report

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Effective Date December 31, 2021

Report Date: March 2, 2022

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DISCLAIMERS AND QUALIFICATIONS

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SYB Group, LLC (“SYB”) was retained by United States Lime & Minerals, Inc. (“USLM”) to prepare this Technical Report Summary (“TRS”) related to Texas Lime Company (“TLC”) limestone reserves and resources. This TRS provides a statement of TLC’s limestone reserves and resources at its mine located in Johnson County, Texas and has been prepared in accordance with the U.S. Securities and Exchange Commission (“SEC”), Regulation S-K 1300 for Mining Property Disclosure (S-K 1300) and 17 Code of Federal Regulations (“CFR”) § 229.601(b)(96)(iii)(B) reporting requirements. This report was prepared for the sole use by USLM and its affiliates and is effective December 31, 2021.

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This TRS was prepared by SYB Group’s President who meets the SEC’s definition of a Qualified Person and has sufficient experience in the relevant type of mineralization and deposit under consideration in this TRS.

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In preparing this TRS, SYB relied upon data, written reports and statements provided by TLC and USLM. SYB has taken all appropriate steps, in its professional opinion, to ensure information provided by TLC and USLM is reasonable and reliable for use in this report.

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The Economic Analysis and resulting net present value estimate in this TRS were made for the purposes of confirming the economic viability of the reported limestone reserves and not for the purposes of valuing TLC or its assets. Internal Rate of Return and project payback were not calculated, as there was no initial investment considered in the financial model. Certain information set forth in this report contains “forward-looking information,” including production, productivity, operating costs, capital costs, sales prices, and other assumptions. These statements are not guarantees of future performance and undue reliance should not be placed on them. The ability to recover the reported reserves depends on numerous factors beyond the control of SYB Group that cannot be anticipated. Some of these factors include, but are not limited to, future limestone prices, mining and geologic conditions, obtaining permits and regulatory approvals in a timely manner, the decisions and abilities of management and employees, and unanticipated changes in environmental or other regulations that could impact performance. The opinions and estimates included in this report apply exclusively to the TLC mine as of the effective date of this report.

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All data used as source material plus the text, tables, figures, and attachments of this document have been reviewed and prepared in accordance with generally accepted professional geologic practices.

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SYB hereby consents to the use of TLC’s limestone reserve and resource estimates as of December 31, 2021 in USLM’s SEC filings and to the filing of this TRS as an exhibit to USLM’s SEC filings.

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Qualified Person: /s/ Keith V. Vickers

Keith V. Vickers, TXPG #3938

President, SYB Group, LLC

1216 W. Cleburne Rd

Crowley, TX 76036

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Table of Contents

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List of Figures

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List of Tables

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1Executive Summary

The Texas Lime Company (“TLC”) mine is a production stage, open pit mine that produces high-grade limestone with calcium carbonate (“CaCO₃”) quality above 96.0% from the Edwards formation that is delivered to TLC’s primary crusher. The TLC plant processes the limestone into various products that are sold to a variety of customers. The TLC mine is located in Johnson County, Texas on approximately 5,200 acres owned by TLC that contains known high-grade limestone reserves in a bed that typically ranges from 25 ft. to 35 ft. Operations began at the TLC mine in the 1940’s.

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Mining at the TLC mine consists of pushing aside the topsoil and overburden using conventional earthmoving equipment and methods. The topsoil and overburden are used as backfill for nearby previously mined pits. The limestone ore body is then drilled and blasted, followed by loading and haulage utilizing conventional limestone mining equipment. The shot limestone is hauled to TLC’s primary crusher.

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The TLC mine has procured, and is operating in compliance with, the required air and storm water permits that are required by the Texas Commission on Environmental Quality. TLC will be required to renew the permits when they expire in January 2026.

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The TLC mine currently averages an annual production rate of approximately 1,400,000 tons of limestone per year. The expected mine life at that rate of production is in excess of 75 years.

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Over the last 65+ years, drilling reports from drilling programs performed and historical production records have established that the Edwards formation limestone has consistent high-grade limestone (CaCO₃ quality above 96.0%) in the TLC mine property. They have also confirmed the 25 to 35 ft. thickness of the Edwards limestone ore interval as well as the relatively shallow overburden that is favorable for open pit mining. The drilling data, along with information from mining faces and examination of widely spread Edwards outcrops, allow a high degree of geological confidence to be assigned to the quality and lateral continuity of the limestone on the property.

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As noted in section 2.1, Keith Vickers of SYB Group (“SYB”), a consultant for United States Lime & Minerals, Inc. (“USLM”) for over 20 years, served as the Qualified Person (“QP”) and prepared the estimates of limestone mineral resources and reserves for the TLC mine. Summaries of the TLC mine’s limestone mineral resources and reserves are shown below in Tables 1.1 and 1.2, respectively. Sections 11 and 12 sets forth the definitions of mineral resources and reserves as well as the methods and assumptions used by the QP in determining the estimates and classifications of the TLC mine’s limestone mineral resources and reserves.

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Table 1.1 Texas Lime Company – Summary of Limestone Mineral Resources as of December 31, 2021,

Based On $11.05 Crushed Limestone ^{1, 2}

Notes: ¹ Price Source from USGS Mineral Commodity Summaries 2021.

² Shot limestone delivered to the primary crusher.

³ N/A: Not Applicable because estimated resources are in place.

Table 1.2 Texas Lime Company – Summary of Limestone Mineral Reserves as of December 31, 2021,

Based On $11.05 Crushed Limestone ^{1, 2}

Notes: ¹ Price Source from USGS Mineral Commodity Summaries 2021.

² Shot limestone delivered to the primary crusher.

The modeling and analysis of the TLC mine’s resources and reserves has been developed by TLC and USLM personnel and reviewed by management of the companies, as well as the QP. The development of such resources and reserves estimates, including related assumptions, was a collaborative effort between the QP and personnel of the companies.

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The TLC mine has been a stable producer of limestone using the current equipment fleet and operating parameters for many years. This operating history and its 2022 budget were used to estimate the unit costs for limestone mining, overburden stripping, and annual sustaining capital expenditures. As the mine plan proceeds further from the existing crushing facility, haulage distance increases. This will require an increase in the haul truck fleet size in some years. Capital and operating costs were adjusted for this increased haulage requirement as shown in Appendix B. The fleet size is three trucks until 2027. From 2027 to 2036, from 2045 to 2052, and from 2100 to

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2102 the fleet size is four trucks. From 2037 to 2044 and from 2053 to 2064 the fleet size is five trucks. From 2065 to 2067 the fleet size is six trucks. Tables 1.3 and 1.4 set forth the estimated capital costs and operating costs, respectively, used to estimate future operations for the TLC mine.

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Table 1.3 Capital Costs

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Table 1.4 Operating Costs

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It is the QP’s overall conclusions that:

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2Introduction

2.1Issuer of the Report

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Mr. Keith Vickers of SYB Group, LLC (“SYB”), a consultant for USLM for over 20 years, prepared this Technical Report Summary (“TRS”) on TLC’s mining operations located in Johnson County, Texas. Mr. Vickers is a Qualified Person (“QP”). USLM is a publicly-traded company on the NASDAQ Stock Exchange under the ticker symbol USLM and TLC is a wholly-owned subsidiary of USLM.

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2.2Terms of Reference and Purpose

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The purpose of this TRS is to support the disclosure of mineral resource and reserve estimates for TLC’s existing mining operations located in Johnson County, Texas, as of December 31, 2021. This TRS is to fulfill 17 Code of Federal Regulations (“CFR”) § 229, “Standard Instructions for Filing Forms Under Securities Act of 1933, Securities Exchange Act of 1934 and Energy Policy and Conservation Act of 1975 – Regulation S-K,” subsection 1300, “Disclosure by Registrants Engaged in Mining Operations.” The mineral resource and reserve estimates presented herein are classified according to 17 CFR § 229.1300 Definitions.

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The QP prepared this TRS with information from various sources with detailed data about the historical and current mining operations, including individuals who are experts in an appropriate technical field. TLC has not previously filed a TRS.

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The quality of information, conclusions, and estimates contained herein are based on: i) information available at the time of preparation; and ii) the assumptions, conditions, and qualifications outlined in this TRS.

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Unless stated otherwise, all volumes and grades are in U.S. customary units and currencies are expressed in 2021 U.S. dollars. Distances are described in U.S. standard units.

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2.3Sources of Information

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This TRS is based upon engineering data, financial and technical information developed and maintained by TLC or USLM personnel, work undertaken by third-party contractors and consultants on behalf of the mine, public data sourced from the United States Geological Survey, Texas Bureau of Economic Geology, internal TLC technical reports, previous technical studies, maps, TLC letters and memoranda, and public information as cited throughout this TRS and listed in Section 24. Table 2.3 is a list of the terms used in this TRS.

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This TRS was prepared by Keith V. Vickers, BSGeol, MSGeol, TXPG #3938, CPetG #6152. Detailed discussions with the following were held during the preparation of the TRS:

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Mr. Timothy W. Byrne, President, CEO USLM, Dallas, Texas

Mr. Michael L. Wiedemer, Vice President, CFO USLM, Dallas, Texas

Mr. Russell R. Riggs, Vice President, Production, USLM, Dallas, Texas

Mr. M. Michael Owens, Corporate Treasurer, USLM, Dallas, Texas

Mr. Jason Nutzman, Director of Legal and Compliance, USLM, Dallas, Texas

Mr. Wendell Smith, Director Environmental, USLM Dallas, Texas

Mr. Julius J. Harris, Vice President and Plant Manager, TLC, Cleburne, Texas

Mr. Peter McKenzie, Mine Manager, TLC, Cleburne, Texas

Mr. Tom Quinlan, Quality Control Laboratory Manager, TLC, Cleburne, Texas

Mr. Keith Vickers, SYB Group, USLM Consulting Geologist, Crowley, Texas

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Table 2.3 Glossary of Terms and Abbreviations

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2.4Personal Inspection

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The QP, who has been a consulting geologist for USLM for over 20 years, is familiar with TLC’s mine geology and operations. In addition, the QP conducted onsite visits to review data, confirm protocols, and gather specific information required for the TRS not previously available to him.

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On September 3, 2021, the QP met TLC personnel in the TLC mine office to review the drill hole and surface sample database and discuss what data was available and needed for the TRS. The QP inspected the mine and reviewed the core storage methods. Core logging and sampling procedures were verified. The QP discussed quality control and quality assurance with the TLC QC/QA lab manager. A review of the core sawing methods and sample preparation for analytical tests also occurred.

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On November 29, 2021, the QP visited the site to update and review a report checklist with TLC management and personnel. Also attending this visit was Mr. Peter Christensen (consultant) to provide clarity and insight into the new SK-1300 regulatory requirements. A review of the resource areas, grade controls, and production hole sampling and surveying procedures occurred at the plant office. The QP also inspected several mined locations in the mine to examine the consistency and thickness of the limestone interval. The mining faces were also compared to the existing geologic model and the QP met with the QC/QA lab manager to obtain lab and X-Ray Fluorescence (“XRF”) standard certifications and instrument service/care contracts. Table 2.4 is a partial list of dates the QP has visited the mine.

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Table 2.4 Visits Made by QP to TLC

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3Property Description

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3.1Property Description and Location

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TLC’s operations (32°15’28.65”N, -97°33’46.41”W, Fig. 3.1, GoogleEarth, 2021) are located in Johnson County, southwest of Cleburne, Texas, 12 miles by a state highway.

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3.2Mineral Rights

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TLC wholly owns in fee (surface and mineral) approximately 5,200 acres with the exception of 333 +/- acres in Tract 1, Abstract 200, in which it owns the entire mineral estate only (no surface) (AcreValue website, 2021) (USLM internal report). Title includes a clause for negotiating the purchase of the surface. Information was furnished by TLC.

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There are no significant issues or risks to work on the properties outside of those generally related to mining operations.

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3.4Lease Agreements and Royalties

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TLC does not receive any royalties as it is not the lessor for any mineral rights on its properties.

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4.1Topography, Vegetation, and Physiography

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The area’s topography comprises broad valleys associated with the Brazos River drainage and abundant small branch valleys extending on either side of the river. TLC’s operations are on one of the ridge and plateau areas. The elevation ranges from 990 ft. to 660 ft. There is little soil covering the rock outcrops along the sides and ends of the ridges; slightly more occurs on top.

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The tree types are consistent with the vegetation typically found in this region. The flat valley floors are primarily agricultural land with hay pastures the dominant agri-businesses.

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The operation is in the physiographic province known as the Grand Prairie (Texas Almanac website, 2019). Rocky soils on limestone units and clay-rich soil developed on shale and clay and marl units characterize this province. Much of the province has thin to no soil thickness that results in a treeless terrain for the most part.

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4.2Accessibility and Local Resources

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Primary access to the operation is by State Highway 67 and then by State Park Road 21 or county road 1434. Cleburne has a population of approximately 30,000 and is served by a municipal airport. Commercial airline travel is through DFW International Airport, 65 miles away. Roads are well paved with broad shoulders and load weight designed for multi-axle trucks. The majority of the operation’s workers live in Johnson County and some live in the surrounding counties.

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4.3Climate and Operating Season

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The average rainfall for Johnson County is 38 inches of rain per year. The County averages one inch of snow per year. On average, there are 231 sunny days per year in Johnson County. The County averages 75 precipitation days per year. Precipitation is rain, snow, sleet, or hail that falls to the ground. The average temperature ranges from a high in July of 95 degrees F. to a low of 33 degrees F. in January (https://www.bestplaces.net, 2021). There are infrequent winter storms that may make operations pause for a day or so but nothing long-term. The above conditions make year-round mine operation possible with little weather-related lost time.

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4.4Infrastructure

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4.4.1Water

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There are no issues with the water supply.

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4.4.2Energy Supply

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Fuel supply for TLC’s mining operations is from distributors in Johnson County.

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4.4.3Personnel

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The DFW Metroplex has a population of 7.6 million and the nearby town of Cleburne has 30,000 people that the mine can draw from for new or replacement employees (U.S. Census website, 2020).

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4.4.4Supplies

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The mine’s supply needs are not an issue since all the major manufacturers have representatives in the DFW Metroplex area. All the major airlines and air freight carriers serve DFW International Airport and the airport is considered a prime hub. Several trucking companies provide service to the operation from Johnson County and the DFW area.

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5History

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5.1Prior Company Ownership

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The TLC mine began operations in the 1940’s. USLM (formerly known as Rangaire Corporation) purchased TLC in the 1960s, which owned 458 acres in Johnson County, Texas, at the time. In the years that followed, TLC acquired additional acres of land resulting in the current ownership of approximately 5,200 acres of land in Johnson County, and built three rotary kilns, two of which have preheaters and are still in operation, as well as other operational and office facilities. Information was provided by TLC.

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5.2Exploration and Development History

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Table 5.2 Historical Exploration and Development Drilling

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Note: A detailed discussion of all drilling and results is in Section 7.1.

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6Geologic Setting, Mineralization, and Deposit

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The TLC mining operation has, and is, mining the upper part of the Cretaceous age Edwards Limestone. The associated lime plant requires unique chemical properties found in the Edwards. The mining operation has been mining continuously for the past seven decades. The longevity of this mine is due to the availability of resources, low chemical variability, and reasonably consistent thickness of the limestone ore mined.

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6.1Regional Geology

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Shallow seas covered Texas during the early Paleozoic (Cambrian-Ordovician), the late Paleozoic (Permian) and the late Mesozoic (Cretaceous). These environments produced the extensive carbonate strata that form the limestone surface belt known as the Edwards Plateau.

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The regional geology consists of northeast to southwest trends of outcropping and subcropping bands of rock groups ranging from the Permian age (oldest) to Eocene age toward the Gulf Coast. The Cretaceous age trend stretches from the border with Oklahoma down through the San Antonio area along with other outcrop trends (Fig. 6.1-1).

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The Fredericksburg Group is part of this series and includes the Edwards Limestone formation. Fredericksburg Group sediments were deposited on an extensive reef bank. This environment covered nearly all of the Midwest of the United States. It was part of a seaway (broad trough) that extended northwest into western Canada (Fig. 6.1-2) (www.cretaceousatlas.org/geology/, 2021).

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6.2Local and TLC Property Geology

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Locally, Johnson County surface geology consists of almost flat-lying strata with the geologic age range of Cretaceous (oldest) and Quaternary (youngest). The units dip east-southeast gently toward the East Texas Basin further to the east. These units are unaffected by the significant faults that bound that basin (Collins and Baumgardner, 2011).

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The structural fabric across the TLC property is straightforward, consisting of a dip with minimal range from two to four degrees to the east-southeast. In the past seven decades, no faulting has been observed on the surface or encountered by drilling or mining. The thickness of the Edwards ore interval ranges from 25 to 35 ft. and covers the entire property except were eroded. Photogeology and surface mapping have determined the outcrop is almost continuous in the area of the TLC property limits. The outcrop pattern reflects the almost flat dip with no subsurface structural relief.

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In 1955, Albert A. Lewis drilled 159 holes on the property and locally. Data from recent holes on the site, contiguous parcels, and measured sections further confirm the same limestone bed is present across the entire TLC property. The Edwards is an almost linear north-south outcrop across the property. This data, along with information from mining faces and examination of nearby Edwards outcrops, provide a high degree of geological confidence of the quality and lateral continuity of the limestone on the property.

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The TLC mine geology is a mirror image of the regional and local geology. The Edwards forms low relief cliffs that are bleached by the sun to bright white. In 1997 TerraCon, Inc. mapped the local area Edwards outcrop using photogeology methods (Bowers and Vickers, 1997). In some cases, the outcrop is hidden by weathering in the Kiamichi shale just above the formation.

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6.3Mineralization

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Unlike other industrial minerals or metal deposits, high calcium limestones are the product of unique depositional environments only, not by subsurface alteration or enhancement. The CaCO₃ content is the product of reef organisms that build their exoskeletons out of CaCO₃ derived from the marine environment. The reef area has very limited or no exposure to non-carbonate materials such as clay, silica, and iron that reduce the CaCO₃ content. No subsurface mineralization has occurred to create or enhance the CaCO₃content in this deposit.

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6.4Stratigraphy and Mineralogy

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The following is a detailed discussion of the mine site stratigraphy. The Fredericksburg Group lithologies reflect changes in shoreline movement. The back-and-forth movement of the shoreline results from sea-level changes. Fig. 6.4-1 is the stratigraphic column for Western Johnson County (Brand, 1953).

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Thin alternating shale and shaley limestone comprise the Walnut formation, deposited in near-shore shallow water such as a marsh or shallow tidal bay. The Comanche formation represents deeper water deposition with limestone beds alternating with widely separated shale layers, such as present in a lagoon or back reef bay environment. The Edwards formation is limestone with no land-derived shale or sand layers. The depositional conditions were clean seawater with moderate depth (sun light), resulting in massive carbonate reefs (Lozo et al., 1959).

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Next, during deposition of the Kiamichi formation, the water depth deepened significantly, stopping nearly all reef production. This water depth change resulted in thick shale beds with very thin limestones and thin sandstones that typically represent deeper offshore areas and are associated with fine grain sediment input. The group’s top and bottom are marked by a depositional hiatus, or erosional surface called an unconformity. These surfaces sometimes represent aerial exposure (dry land) and sediment removal. Fig. 6.4-1 contains the Fredericksburg Group stratigraphic sequence, thickness range, and lithology (Brand, 1953). Table 6.4 shows a stratigraphic order and thickness of the mined strata on the site. A cross-section index map with a north-south cross-section from the TLC mine is shown in Fig. 6.4-2.

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Table 6.4 TLC Property Stratigraphy

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7Exploration

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The sample database used for the TLC geologic model is composed of multiple sources of data types. These sources include core and percussion drilling, measured sections with outcrop or highwall sampling, and photogeology mapping the Edwards limestone outcrop beyond the operation. Because of the TLC’s significant land position, little exploration drilling has been necessary for the last 60 years. A considerable amount of the recent drilling has been near the mine and on TLC property.

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7.1Drilling Programs

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A summary of all drilling projects in the local vicinity and on TLC property is in Table 7.1-1. These projects include exploration, development, and production drilling by diamond and percussion bit methods.

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Table 7.1-1 All TLC Drilling Projects

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Fig 7.1-1 is a map of all core hole drilling programs utilized in the geologic model with labeled resource areas. A list of the hole database containing the hole name, XY coordinates, can be found in Appendix A.

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Before 1955, TLC leased a mining property in Johnson County. To secure ownership of mining properties and extend resources, TLC sponsored an extensive exploration and development drilling program conducted by Albert A. Lewis P.E./Geologist in 1955 and 1958. These programs core drilled in southwestern Johnson County. The exploration area centered around the current mining area (Wilbanks Tract, Lewis, 1955). The program consisted of 189 core holes and provided detailed information when the Edwards was present. The program results led to the purchase of the first mining properties at the TLC’s present-day location.

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The average CaCO₃ percentage for entire 189-hole project was 97.9%. Table 7.1-2 lists the drilling results for properties located at the current mine site. The consistent CaCO₃ quality and thickness results from this detailed drilling was evidence that drill hole spacing was not a limiting factor in confirming continuity and consistency of the Edwards limestone. Summary tables for each parcel are in the internal reports. After review and verification, it was evident that the quality limit resulted in CaCO₃ percentages above 96.0% for the majority of the properties drilled.

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Table 7.1-2 Summary of 1955 and 1958 TLC Mine Site Drilling*

Note: *From Lewis, 1955 and 1958 internal drilling reports.

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The core sampling and logging methods employed in the 1955 and 1958 drilling are comparable to modern-day techniques. Lewis reported the county surveyor surveyed the hole locations that produced maps for the reports’ resource calculations. The reports do not contain the hole location coordinates. The reports have hole location maps for the leased and acquired tracts and provided property location maps for all the drilled properties.

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During drilling, cuttings and core were collected. In the locations where the overburden was absent, cuttings were collected until enough hole was drilled to set up the core barrel assembly. An air compressor was used to clean the holes and retrieve the cuttings while drilling. A cone rock bit was used to drill the cuttings which produced coarse (-0.5 inch) cuttings. Samples were collected in the box from a pipe that ran to the collar flange over the hole. A sample was taken and bagged and the hole was blown clean every two ft. After five ft., the composited sample in a bag was labeled internally and externally. The collection box was then cleaned and the hole blown clean before the next composite. Hole locations with nearly ten ft. or more of overburden core drilling were started as soon as solid bedrock was drilled. The cuttings and core were logged at the hole site. The data logged were core recovered, stratigraphy, lithology, and stratigraphic top and bottom.

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The reports provided detailed drill logs and laboratory result sheets. Holes, where mapped locations are provided, are material to developing the geologic model. The chemical analysis results are very comparable to analysis from holes recently drilled. These drilling reports establish that the Edwards limestone has consistent CaCO₃ quality above 96.0% around the current TLC operation site.

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In 2016, additional development core drilling was done to support the mine advancement (Fig. 7.1-1). A twelve-hole program was approved and followed the core logging and sampling USLM protocols. The holes were located by GPS unit and logged at the location. The TLC QC/QA lab conducted the XRF analysis. The results of this drilling and analysis are very comparable to the results from the other core projects. A summary of these results is presented in Table 7.1-3.

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Table 7.1-3 Summary of 2016 Development Drilling

Note: From 2016 SYB Group Drilling Report.

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The chemical results were consistent with the core analyzed in the 1955 drilling programs.

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The most recent exploration project occurred on land now owned by TLC. The land adjoins the mine property east of State Park Road 21. The drilling program consisted of eight core holes on the sale tract and four were drilled on adjacent TLC property to the west. The Edwards Limestone quality and minable thickness were confirmed on both parcels and the sale tract was purchased. Table 7.1-4 contains a summary of the drilling results. The holes were surveyed by a GPS unit and logged at the location according to the core logging protocols USLM had established. The TLC QC/QA lab conducted the XRF analysis.

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Table 7.1-4 Summary of 2018 Exploration Drilling

Note: From 2018 SYB Group Drilling Report.

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The CaCO₃ percentage results were consistent with the drilling results in the active mine areas. Depths of the east drilling Edwards tops and bottoms compare well with the 2016 TLC drilling tops and bottoms, confirming a nearly flat-lying formation with a low dip range from two to four degrees to the east-southeast. The protocols for the project are presented below in this section.

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TLC has for many years conducted development drilling and sampling on the properties being actively mined. This drilling has consisted of percussion (test holes) and coring to provide geology/lithology, quality control, and data to confirm or update the mine geologic model.

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The current protocols for drilling, logging, and sampling cores have been developed over several years as equipment and analyses have changed. Contract geologists selected all core drilling locations with the approval of sites and drilling budget by USLM/TLC management. Core drilling was conducted directly under the supervision of contract geologists. All core was logged by SYB Group or an approved USLM contract geologist using a protocol modified from the Shell Sample Examination Manual (Swanson, R.G, 1981) that was modified by SYB Group and approved by USLM.

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Immediately upon retrieval, the core was placed on a V-shaped trough. All core pieces were fitted together and labeled with a permanent marker in one-foot intervals. Next, characteristics related to the suitability of the limestone for the TLC plant processing and geology are recorded. These items are stratigraphy, key marker lenses/layers, lithology characteristics, visual identification of ore top and bottom, and structural disturbance. The core from each drill hole was placed into cardboard boxes in two-foot intervals totaling 10 ft. at the drill site. The boxes were labeled with a box number, company information, hole number, core runs, and depths marked on each box. The boxes were then delivered to the TLC core storage warehouse. The contract geologists were responsible for examining the core and compiling a detailed interval list for XRF analysis. This list was later entered into Excel to build an analysis database. The intervals were two ft. long and included intervals six to ten ft. above and below the lithologically identified ore zone. This excess is so the top and bottom of the ore could be chemically defined.

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Once the cores were at the core storage area, the core intervals were diamond sawed into two-thirds to one-third splits. The interval’s one-third split was then bagged in a plastic bag and labeled with the depth interval to be analyzed. The bagged intervals are kept in plastic labeled buckets or boxes in separate groups by the hole and then submitted to the TLC QC/QA lab for XRF analysis. Any portions of samples not destroyed during the testing process are stored at TLC’s core storage facility.

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The percussion development or test hole drilling is ongoing. A hole is drilled as soon as new land is cleared, stripped, or new access to an area right above the top of the Edwards is available. Locations are selected to provide data points providing closer spacing to the core locations. Mine drilling crews performed test hole logging primarily but contract geologists logged the holes when needed. This program is utilized to confirm (pit specific) the mine geologic model and verify the CaCO₃ content between core holes. These holes were sampled by catching drill cuttings in a container next to the hole or from the cyclone dust collector, depending on the drill utilized while drilling the desired interval of five or two ft. The hole is then swept by cycling the drill string up and down while blowing the hole clean. The upper interval above is drilled and sampled if the hole location is not directly on top of the ore zone. This non-ore interval thickness is minimized so that contamination from above is not a concern. A 20-mesh steel screen is used to separate dust and fine particles to obtain the largest chip sizes for visual examination and XRF analysis.

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Production holes are selected from the blast hole patterns and are part of a weekly quality control program that existed for most of the mine’s life. These holes provide detailed bench-specific chemical quality and ore zone thickness data. The production hole results were not included in the TRS resource estimate because of the missing location information and high spatial density of data (model biases).

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Holes were surveyed using GPS (WAAS and GLONASS capable) units. After surveying by drone (Firmatek Inc.), some locations are checked to be verified. When adjustment was needed in the horizontal plane, it was usually under 10 ft.

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The lithology, chemical analysis, and ore interval for all database holes were plotted as logs. A recent core log is shown below in Fig. 7.1-2. These logs were used to correlate stratigraphy, lithology, and ore zone intercepts. Also, they form a visual catalog for the hole data. Sources for this section were TLC personnel and historical reports.

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7.2Surface Mapping and Sampling

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Outcrop section sampling and measuring had occurred when access for a drill was problematic or offsite. These sampling programs were conducted at TLC in 1998, 2015, 2017, and 2020 to locate and describe sample outcrops and extend the geologic database. A representative section was measured at each location, samples were collected, and the lithology was described. These sampling sites were used to provide chemical quality and surface mapping of the limestone units in and beyond the boundary of the active mining operation. The outcrop or highwall sampled section was surveyed by GPS and marked on aerial photos. Representative hand samples were obtained from each section, where access would allow, by a hammer. The piece was prepped, so only fresh material was present. The sample and a plastic zip bag were labeled with a permanent marker with the sample number. Samples were submitted to TLC QC/QA lab for prep and XRF analysis. A profile was made for each section using USGS LIDAR scanned topography, and outcrop samples were plotted with CaCO₃ percent results on the profile.

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The N. West section was measured to confirm the presence of the Edwards and validate three holes drilled there because specific locations could not be established. Table 7.2 summarizes outcrop measured sections and the average CaCO₃ percentage for the section. Fig. 7.2-1 is an example of a measured section profile (N. West) with outcrop sample locations marked.

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Table 7.2 Summary of Measured Section Sampling

Note: * Drilling was stopped in the ore interval.

The drilling, surface sampling, and mapping results have provided the following conclusions. Locally, the Edwards outcrop is almost continuously visible across the TLC area. Recent sampling confirmed the mapping by photogeology by TerraCon, Inc. in 1997. This mapping confirmed, and drilling has substantiated, the presence of the limestone throughout the TLC property. Sources for this section were consultants and TLC.

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7.3Hydrogeology Information

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No hydrogeological studies have been conducted at the TLC property and the State of Texas does not require TLC to do so. Because the floor of the TLC mine is above the groundwater table.

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7.4Geotechnical Information

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The state of Texas does not require geotechnical studies to be performed at mines.

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8Sample Preparation, Analyses, and Security

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8.1Sample Preparation and XRF Analysis

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The TLC plant produces many products which are under strict quality parameters for chemical and physical quality. The TLC QC/QA lab was established many years ago and has been upgraded as required to meet the increasing demands of the customer base. In addition, customer quality control labs test TLC product shipments frequently.

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XRF is one of the primary methods for determining the chemical content of limestone. The TLC QC/QA lab has been responsible for conducting XRF analysis on plant products and all limestone samples from stockpiles, belt feed samples, drilling, to hand samples collected for outcrop conformation. The five significant oxides are analyzed. CaO is most important because of the plant’s raw limestone requirement above 96.0% CaCO₃.

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XRF sample preparation, whether core or cuttings, is crushed the entire sample to -10 mesh. The sample is then separated and reduced by a ruffle to 250 grams, drying and pulverizing a representative split to -150 mesh. The samples are analyzed for these oxides CaO, MgO, Fe₂O₃, Al₂O₃, and SiO_2, following USLM’s XRF analytical method for limestone analysis. The technique involves pressing the powder into a pellet using a wax binder to hold the shape. The sample trays are loaded into the instrument with samples, a copper standard, and a certified control standard. The analytical procedure and protocol information was provided by TLC QC/QA personnel and other information for this section was provided by TLC personnel.

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8.2 Quality Control/Quality Assurance

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The unknown samples are analyzed twice in a run to provide data to confirm repeatability. All sample preparation equipment is cleaned after preparing each sample and before the subsequent preparation. The instrument is cleaned and calibrated each year by the manufacturer and is under a service contract. Whenever the device becomes dirty and registers out of calibration or out of specification for the standards, the manufacturer comes out to clean, recalibrate, and repair if necessary. The oxide results of each sample are totaled to determine if the data is within an acceptable error range around 100%. The sample analysis is rerun if the total oxide percentage exceeds acceptable error limits. Sample preparation and a newly prepped sample correct the problem in many cases. The lab has a set of certified limestone standards to cover the content range of the major oxides that can occur in limestones. The appropriate standard is run concurrently with the unknown samples. The standard results are compared run to run to ensure the instrument operates correctly.

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USLM has a total of four QC/QA labs among its wholly-owned subsidiaries. These labs can perform many of the same analyses, specifically XRF. At any time one lab goes down or needs verification of analytical (XRF) results, samples can be sent to another lab for continuing analysis of the sample or cross verification.

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The TLC QC/QA lab is certified by:

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The lab follows procedures and protocols set forth by:

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The lab utilizes certified limestone samples to verify the accuracy and calibration of its instrumentation. These are:

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The security for limestone geological samples is not required as compared to the procedures needed for precious metals (gold, silver, etc.). Core or other samples are, immediately after drilling, taken to the core storage area by the contract geologist, member of the drill crew, or the collector of limestone samples. They are logged in and then processed by TLC QC/QA lab personnel. The change of possession is limited to two or three people that can be identified and held accountable for the whereabouts of the samples before delivery to the lab. This information was provided by TLC QC/QA lab personnel.

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8.3 Opinion of the Qualified Person on Adequacy of Sample Preparation

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The QP noted the adherence to preparation and analytical procedure protocols by the TLC QC/QA lab personnel. The analysis of geologic samples is conducted with the same care as the TLC QC/QA testing for the products produced by the plant. The opinion is that the analytical program and lab provide reasonably accurate data for determining resource estimates.

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9 Data Verification

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9.1 Source Material

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The QP worked with onsite TLC personnel to obtain databases and raw data. There was an ongoing interface with TLC personnel while reviewing and verifying the data needed to model the resources. For this TRS, the hard copy data was compared with the digital database for correctness and thoroughness. The data from the old drilling programs were validated as reasonably as possible by comparing lithology and depths from nearby recent holes. Recent hole ore intercepts were cross-checked with the appropriate mine surveys to verify and confirm surveyed collar data.

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The 1955 hole maps with the plotted surveyed locations were georeferenced using Global Mapper^TM and then digitally overlain on age appropriate USGS Quad Geotiff raster maps to verify location and, when possible, topography (USGS MapView, https://ngmdb.usgs.gov/topoview/viewer).

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When possible, the original hole analyses were re-composited using a cutoff above 96.0% CaCO₃ cutoff. Then CaCO₃ averages were compared to recent holes. The selected core from the recent drilling was compared to drill site core logs to confirm logging was suitable for the intercept data needs. The QP met with the QC/QA lab manager to validate that the QC/QA protocol was followed for the geologic samples and the instrument’s status records. The sources for this data are the TLC QC/QA lab, contract geologists, and Firmatek Surveying.

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A truck LIDAR or drone photogrammetry elevation survey provides spatial control for TLC mining. These surveys are conducted quarterly and year-end. They are accurate to within one foot when coupled to a Trimble ground station. (Firmatek, 2020). All surface mapping and sample locations were surveyed by hand-held GPS and adjusted where necessary when compared with federal government or private LIDAR data sources. Locations for select accessible sites were survey-checked with GPS for validation.

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9.2 Opinion of Qualified Persons on Data Adequacy

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After contacting TLC personnel and subcontractors, reviewing the material, and performing verification processes, the QP is satisfied the drill hole database and chemical analysis data are reasonably valid. The QP’s opinion is that the data has been analyzed and collected appropriately and reasonably and that the data was adequate for the resource interpretation and estimation.

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10Mineral Processing and Metallurgical Testing

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The limestone mined at the TLC property is sedimentary without alteration due to metamorphic or igneous geologic processes. The uniqueness and suitability of the raw stone for making the plant’s products are based on the percent of CaCO₃ content in the limestone. There is no metal content in the ore and no need to perform metallurgical testing. Shot limestone from the mine has been supplied to the plant’s primary crusher for many years. The mine does not operate crushing and screening processes, so testing is unnecessary. TLC personnel furnished the preceding information.

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11Mineral Resource Estimates

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11.1Definitions

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A mineral resource is an estimate of mineralization, considering relevant factors such as cutoff grade, likely mining dimensions, location, or continuity, that, with the assumed and justifiable technical and economic conditions, is likely to, in whole or in part, become economically extractable. Mineral resources are categorized based on the level of confidence in the geologic evidence. According to 17 CFR § 229.1301 (2021), the following definitions of mineral resource categories are included for reference.

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An inferred mineral resource is that part of a mineral resource for which quantity and grade or quality are estimated on the basis of limited geological evidence and sampling. An inferred mineral resource has the lowest level of geological confidence of all mineral resources, which prevents the application of the modifying factors in a manner useful for the evaluation of economic viability. An inferred mineral resource, therefore, may not be converted to a mineral reserve.

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An indicated mineral resource is that part of a mineral resource for which quantity and grade or quality are estimated on the basis of adequate geological evidence and sampling. An indicated mineral resource has a lower level of confidence than the level of confidence of a measured mineral resource and may only be converted to a probable mineral reserve. As used in this subpart, the term adequate geological evidence means evidence that is sufficient to establish geological and grade or quality continuity with reasonable certainty.

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A measured mineral resource is that part of a mineral resource for which quantity and grade or quality are estimated on the basis of conclusive geological evidence and sampling. As used in this subpart, the term conclusive geological evidence means evidence that is sufficient to test and confirm geological and grade or quality continuity.

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11.2Key Assumptions, Parameters, and Methods

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11.2.1Resource Classification Criteria

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Geologic and analytical data from regional and local drilling along with surface sampling/mapping have proven that the Edwards limestone has a consistent CaCO₃ content above 96.0% and a small range of thickness (25 ft. to 35 ft.) across many square miles of outcrop area in Johnson County. These analytical results cover from 1955 to 2021 and are sufficient to establish reasonable certainty of geological presence, grade, and quality continuity on the property.

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Practically any outcrop of the Edwards limestone on the TLC property will supply limestone with a CaCO₃ above 96.0%. The many years that the TLC mine has operated historically proves the extraction of the deposit is economical. The geologic confidence is high with the abundance of verified sampling, classifying these resources in the measured category is appropriate.

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11.2.2Market Price

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A reasonable market survey for industrial mineral prices is conducted by the USGS each year. The publication is titled “USGS Mineral Commodity Summaries 2021.” Their database is comprised of sources from the entire United States. The study considers such material issues as regional price differences, weather effects, production issues, and decreased demand from downstream users. For 2020, USGS reported an average value price crushed limestone per metric ton of $12.19, which converts to $11.05 per short ton for crushed limestone. TLC mine’s only product is shot limestone and is the sole supplier to the TLC plant.

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11.2.3Fixed CutOff Grade

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The TLC mine supplies shot limestone to the plant’s primary crusher and is further processed by the Texas Lime Company plant for products to sell to end-user markets. The plant must be provided with a limestone source above an average CaCO₃ threshold for customer needs. No matter the product, the raw limestone must exceed a minimum average content above 96.0% CaCO₃. This percentage is considered a fixed cutoff grade because the percentage does not vary for the current plant products. The average percent of CaCO₃ can be higher but not lower to meet the quality requirement of the plant. Mining stone with a significantly higher average CaCO₃ percentage results in the deposit being high-graded which shortens the mine’s life. Lowering the grade is unacceptable for the plant.

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A primary XRF analysis quality control check is to total all the oxide percentages to determine how close the analysis total is to 100%. CaO is the primary oxide of the sample analyzed and the remainder is comprised of MgO, Fe₂O₃, Al₂O₃, and SiO₂ (refer to Section 8).

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Since the mine operates on a fixed cutoff grade, there are no specific economic criteria for changing the cutoff grade. Any cost factors that increase the mining cost of limestone at this cutoff grade would be offset by appropriate downstream price increases in the TLC plant’s products. The fixed cutoff grade determines the ore body thickness, an economic limit because of high stripping ratios.

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11.2.4Summary of Parameters

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Modifying factors are the fixed cutoff grade, the final pit shell area, and property line offset. Key assumptions and parameters applied to estimate mineral resources are in Table 11.2.4

Table 11.2.4 Resource Parameter Assumptions

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11.3Resource Model

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The beginning of the database came from the exploration programs in 1955 and 1958 and continued with the development test completed by TLC to continue to define the resource. This same database was updated in 2016 when development drilling occurred west of the mine. The QP reviewed the existing database, added new sample data, and verified to prepare for the TRS resource estimates. Table 11.3 lists the number of holes in the database and the data type.

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Once the database had been updated a final data entry check was performed. Any sample data without a verifiable location was deleted or excluded. All production hole data was excluded because a significant number of the holes had no location data. Based on the QP’s professional judgment, holes in that category were removed rather than selectively including some holes.

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The mine is surveyed by Firmatek drone photogrammetry quarterly. The survey is accurate to one foot when coupled with a Trimble R8 GPS base station (Firmatek, 2020). The new survey is edited into the old topography using Global Mapper^TM software. The current scan dated October 9, 2021, was used for the TRS resource estimate. The existing coordinate system was State Plane NAD 83 ft. and was not changed.

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The ore body consists of a single limestone bed defined by top and bottom surfaces. The top and the bottom ore intercepts were created from total hole ore composites. The average CaCO₃ percentage is composited above 96.0% in each hole. If any hole’s composite were below 96.0%, that area would be excluded from the resource estimate. This situation did not occur. Next, the hole intercepts and data points from the surface sections were utilized to produce top and bottom three-dimensional structural surfaces or contour maps based on the fixed cutoff grade composites.

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The method chosen to model the deposit structure was gridding using SURFER^TM software and Kriging was selected from twelve other algorithms. The selection process involved four steps:

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These two surfaces were then truncated against the new topography to account for erosional effects. This truncation is done because the ore bed position does not occupy the floor of the valleys. There are several ft. of non-ore below the bottom of the ore. Fig 11.3 is a map of ore thickness (isopach). Some of the older mined areas where backfilled are noted.

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Next, ore isopach, overburden isopach, and overburden stripping ratio maps were constructed. These maps were compared to a block model created in Surpac ^TM using the two ore boundary surfaces. The surfaces were also used to determine conformity and validate the block model. The block model was then utilized to design pits for mine planning and determine mine resource and reserve estimates. Those pit designs furnished the pit shell for defining the outer boundary for resource estimation. The methods employed using Surpac are discussed below.

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The resources were estimated using Geovia Surpac software. Contours of the top and bottom of the ore were imported into Surpac in AutoCAD format exported from SURFER. Surpac DTM surfaces were created using these contours. The same drone survey performed on October 9, 2021 was imported into Surpac. Block models were developed for the resource areas on the property (refer to Fig. 11-3). The blocks were 20 ft. northing by 20 ft. easting and 2 ft. thick. The blocks were coded above or below the topography, above the ore bottom surface, and below the top ore surface. The blocks were coded within the resource boundaries for each area. Mine pits were designed using a 70-degree slope in limestone and a 45-degree slope in the overburden. The crests of the pits were offset 20 ft. from any external property boundaries.

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Table 11.3 Summary of Drill Hole Database for the Model

*Note: Replaced by measured section, chemistry valid.

11.4Mineral Resources

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11.4.1Estimate of Mineral Resources

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The estimate of measured and indicated mineral in-place limestone resources for the TLC operation effective December 31, 2021, estimated from applying the resource parameters to the geologic model are in Table 11.4.1. There are no indicated nor inferred mineral resources.

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Table 11.4.1 Texas Lime Company – Summary of Limestone Mineral Resources as of December 31, 2021,

Based On $11.05 Crushed Limestone ^{1, 2}

Notes: ¹ Price Source from USGS Mineral Commodity Summaries 2021

² Shot limestone delivered to the primary crusher.

³ N/A: Not Applicable because estimated resources are in place

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11.4.2Geologic Confidence and Uncertainty

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The most uncertainty in the geologic data was associated with production hole locations. As discussed in Section 11.3, excluding that data removed the issue. The older chemical analysis consistently reports higher CaCO₃ results than recent data (Lewis, 1955). The older holes were composited at a higher cutoff than the current holes. The company mined through the older areas with no reported quality problems. The Edwards is a tabular, massively bedded limestone. For many decades, the TLC mining operation has produced crushed limestone meeting or surpassing the quality limits required by the plant. The continuity and quality consistency has been documented by abundant widespread local sampling and drilling results on the property. Because of those results, there is high confidence in the definition of the ore zone limits and that the quality is constantly above the CaCO₃ cutoff.

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11.5 Opinion of the Qualified Person

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There are no significant factors onsite that will impact the extraction of this ore body. Most directly involve the TLC plant and not the mine. After reviewing the resource model, the QP is confident that sampling the property at any Edwards outcrop in the area would provide a minable section provided erosion has not removed significant limestone thickness. TLC will continue to economically extract limestone above the quality cutoff for the foreseeable future.

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The QP’s opinion is that the following technical and economic factors could influence the economic extraction of the resource but the TLC plant insulates most of them from the mine. If lime production becomes economically unfeasible, the TLC plant would no longer require limestone from the TLC mine for the production of lime.

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·Environmental Matters:

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Mineral resources were converted to reserves using a 95% recovery factor. The ore that was not recovered was added to the non-carbonate material volume. The property boundary offsets and pit slopes were included in the resource estimate. The limestone is mined on a bench and breaks cleanly from the overburden. The limestone below the targeted pit floor has slightly lower quality and when encountered is blended with higher portions of the ore body without having a significant impact on quality. Dilution volume is minimal and was not estimated.

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As discussed in Section 11.2.3, the average stripping ratio for the reserves is 1.0 tons of stripping per ton of limestone. The highest annual stripping ratio in the life of mine plan is 1.8:1.

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12.1Definitions

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Mineral reserve is an estimate of tonnage and grade or quality of indicated and measured mineral resources that, in the opinion of the qualified person, can be the basis of an economically viable project. More specifically, it is the economically mineable part of a measured or indicated mineral resource, which includes diluting materials and allowances for losses that may occur when the material is mined or extracted (Dorsey, 2019).

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Probable mineral reserve is the economically mineable part of an indicated and, in some cases, a measured mineral resource.  For a probable mineral reserve, the qualified person’s confidence in the results obtained from the application of the modifying factors and in the estimates of tonnage and grade or quality is lower than what is sufficient for a classification as a proven mineral reserve, but is still sufficient to demonstrate that, at the time of reporting, extraction of the mineral reserve is economically viable under reasonable investment and market assumptions (Dorsey, 2019).

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Proven mineral reserve is the economically mineable part of a measured mineral resource.  For a proven mineral reserve, the qualified person has a high degree of confidence in the results obtained from the application of the modifying factors and in the estimates of tonnage and grade or quality. Proven mineral reserve is the economically mineable part of a measured mineral resource and can only result from conversion of a measured mineral resource (Dorsey, 2019).

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12.2Price

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A reasonable market survey for industrial mineral prices is conducted by the United States Geological Survey each year. The publication is titled “USGS Mineral Commodity Summaries 2021”. Their database comprises sources from the entire United States and considers such material issues as regional price difference, weather effects, production issues, and decreased demand from downstream users. As stated in Section 11.2.2, USGS reports average value price for crushed limestone of $12.19 per metric ton, which converts to $11.05 per short ton. The TLC mine is the sole supplier of crushed limestone to the TLC plant.

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12.3Costs

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Annual maintenance of operations capital costs were estimated using prior-year capital expenditures and TLC’s 2022 capital budget. Limestone mining costs for TLC were estimated using historical data and its 2022 budget. Contract limestone mining costs for the TLC East area were calculated using a vendor quote. Stripping costs were estimated using an existing stripping contract cost.

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12.4 Reserve Estimates

The estimate of proven and probable limestone reserves for the TLC operation effective December 31, 2021, estimated from applying the reserve parameters to the geologic model are in Table 12.4.

Table 12.4 Texas Lime Company – Summary of Limestone Mineral Reserves as of December 31, 2021,

Based On $11.05 Crushed Limestone ^{1, 2}

Notes: ¹ Price Source from USGS Mineral Commodity Summaries 2021

² Shot limestone delivered to primary crusher.

12.5 Opinion of the Qualified Person

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TLC has successfully mined this resource for many years using the same methods that are projected into the future. Significant increases in the cost of mining coupled with large decreases in the selling price of limestone would be required to make mining uneconomic. Historically, TLC has been able to increase sales prices in line with cost increases. The limestone and the overburden are consistent across the reserves and allow for stable operating requirements from year to year.

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13Mining Methods

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13.1Geotechnical and Hydrologic Considerations

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The State of Texas currently does not require geotechnical or hydrology modeling in mining operations. Since the operation is a open pit mine, no geotechnical or hydrological studies or models were needed.

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The only geotechnical aspect of the mining investigated is modifying the blasting procedure to control the sizing of the shot limestone. The only investigation into hydrologic conditions in the mine was to confirm drainage patterns and formation dip in the floor so that rainwater could be controlled at the mining face. The floor of the mine is above the water table of the area.

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13.2Mine Operating Parameters

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The TLC mine currently averages an annual production rate of approximately 1,400,000 tons per year. The current expected mine life at the average rate stated is in excess of 75 years.

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Topsoil and vegetation are pushed aside utilizing conventional mining equipment. Some overburden is drilled using a five inch bit. The spacing is determined by using best mining practices. The mining contractor removes the shot overburden using conventional mining equipment. The overburden is backfilled into a nearby pit after the limestone has been extracted. The average stripping ratio for the life of mine is 1.0, with the highest stripping ratio of 1.8 and the lowest of zero. The standard deviation of the annual stripping ratio over the life of the mine is 0.5. This low standard deviation shows that the stripping requirements are relatively uniform from year to year.

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The lowest strata of overburden is a shale layer that breaks away cleanly from the limestone ore body. The limestone ore body is drilled with a five-inch bit. The burden and spacing for the drill hole pattern are determined by using best mining practices. The limestone ore body mining thickness typically ranges from 25 ft. to 35 ft. Blastholes are sampled as required to confirm CaCO₃ content and the desired mining thickness. The limestone is mined with conventional mining equipment. The mining recovery is estimated to be 95%.

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13.3Mining Plan

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Mining operations at the TLC property are straightforward and relatively simple. The overburden material is removed by contract stripping annually. This removal is not generally considered a capitalized activity and is expensed as incurred. It is simply the most efficient and economical way to handle the overburden. Mining operations are a repeated cycle of drilling and blasting the limestone benches followed by loading and haulage. TLC performs the drilling and a contractor carries out the blasting operations. The mine completes the load and haul operations using conventional mining equipment with a small ancillary equipment fleet, including a water truck, grader, and tracked dozer. Limestone is hauled to the primary crusher.  

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13.4Mine Plant, Equipment, and Personnel

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The mining equipment fleet consists of three haul trucks, two loaders and a drill. Ancillary mobile equipment includes a water truck, a grader, an excavator, a dozer, and light vehicles. Contractors have additional equipment for blasting and overburden removal operations. Equipment necessary for mining operations includes three water pumps. The TLC mine operates 5 to 6 days per week depending on demand from the plant and maintenance requirements. Operating personnel, excluding contract operations, consist of nine operators and two maintenance personnel, with a mine manager supervising the operations. The TLC plant personnel and equipment are not discussed because the mining operations end at the plant’s primary crusher. Fig.13.4 shows the TLC estimated final pit boundaries.

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14Processing and Recovery Methods

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14.1Process Plant and Description

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This section does not apply to the report because the TLC mine delivers shot limestone to the TLC primary crusher, where the plant processes the limestone into various products. Crusher Flow Sheet was not included in this TRS because it only covers mined limestone delivered to the TLC plant’s primary crusher.

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14.2Plant Throughput and Design

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This section does not apply to the report because the TLC mine is the sole limestone supplier to the TLC plant’s primary crusher.

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14.3 Plant Operational Requirements

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This section does not apply to the report because the TLC mine is the sole limestone supplier to the TLC plant’s primary crusher.

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14.4Application of Novel or Unproven Technology

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Mining operations at the site follow standard open pit methods. There has not been any application of novel or unproven technologies or techniques.

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15Infrastructure

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The TLC property is accessible by a paved state highway and the TLC mine operation by gravel roads and haul roads is maintained by the mine personnel. The mine site is a land-locked location with no rail or port facilities access. The mine has an office and maintenance shop near the primary crusher. Three-phase electric power is provided to the site via above-ground utility lines. Water is available, including dust control water for the mine, from a TLC-owned well on the property and potable water from the county system. Shot limestone haul truck load-out to the primary crusher is on the mine property. Crushed limestone stockpiles are within the plant area. Shot limestone stockpiles and overburden piles are located in appropriate locations in the mine area. A natural gas system pipeline crosses the property along the western side of the active mining area (Fig.15.1). Several natural gas well pads and production lines, not owned by TLC, are on the property. These locations were preapproved by USLM management and situated to minimize hindrance to the mining process (in valleys or mined-out areas). The associated wells and surface equipment are readily identified and fenced according to the regulations established by the Railroad Commission of Texas. Fig. 15.1 shows an aerial photo of the mine area and significant infrastructure features.

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16Market Studies

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16.1 Market Outlook and Forecast

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Demand for limestone produced at the TLC mine is exclusively for TLC’s lime and limestone production facilities next to the mine which has been in existence for over 70 years and primarily serves the DFW market area.

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Demand for limestone for the TLC operations has averaged approximately 1,400,000 tons per year over the previous five years. Primary demand for lime and limestone products from TLC’s operations is from stable markets including the construction industry, paper and glass manufacturers, municipal sanitation and water treatment facilities, roof shingle manufacturers, poultry and cattle feed producers, and oil and gas services industries. Current market conditions for these customers should result in continued steady demand for lime and limestone products in TLC’s market areas for the foreseeable future.

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16.2 Material Contracts

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The TLC mine is the sole provider of limestone to TLC’s lime and limestone production facilities. There are no material contracts with outside purchasers.

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17.1 Environmental Studies and Permitting Requirements

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The State of Texas has abundant laws and regulations pertaining to surface mining and reclamation for petroleum and coal resources; however, there are little to no regulations relating to other mineral resources, including limestone. Nearly all lands in Texas are privately owned and rarely state or federally owned. A private landowner is free to develop and use non-petroleum resources on his land. Other than environmental regulations, the State of Texas does not require a mining/reclamation permit to operate a limestone mine on private land. USLM furnished the environmental permit information provided in Table 17.1 consisting of the permits associated with the mine.

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Table 17.1 Mining and Environmental Permits

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The above-referenced air permit covers the mine’s shot limestone load-out area at the plant’s primary crusher and the rest of the non-mining operational areas. The stormwater permit covers weather-related discharge throughout the operations, including the mine areas.

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17.2 Overburden, Site Monitoring, and Water Management

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Non-Production mine material consists of overburden with a minor amount of unusable limestone from the blasting process. Considerable natural erosion has occurred in areas at the mine site. Large areas exist where there is little to no overburden over the ore zone. When mining progresses into areas with overburden, it is utilized to backfill the active pits to the extent the material is available.

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The only water used in the mining operation is for dust control. Stormwater is allowed to run off by way of pre-existing natural erosion pathways. In some areas, stormwater must be pumped to a natural drainage from a mine sump used to control standing water at the mining face. The TLC mine area is situated above the natural water table. There are no natural artesian springs or flowing water outlet points associated with mining areas. Therefore, there is no requirement or need for groundwater monitoring. There are no existing environmental site monitors related to the mine.

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17.3 Post-Mining Land Use and Reclamation

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The State of Texas has no standard reclamation regulations for mine closure at this time. Currently, the mining operations use the stripped overburden to backfill the active pit as the volume allows. The estimated life of the mine is in excess of 75 years.

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17.4 Local or Community Engagement and Agreements

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The operation has developed relationships over the years with various neighboring communities, including the adjacent Cleburne State Park.

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17.5 Opinion of the Qualified Person

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Texas is a heavily regulated State of environmental laws and regulations and has numerous permits that require ongoing compliance and oversight from the State agency. TLC and USLM personnel are well trained and stay up to date on all environmental regulations. All permits require constant reporting and oversight from the State environmental agency. In the QP’s opinion, there are no current or outstanding issues in environmental governance.

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18Capital and Operating Costs

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The TLC mine has been a stable producer of limestone using the current equipment fleet and operating parameters for many years. This operating history and its 2022 budget were used to estimate the unit costs for limestone mining, overburden stripping, and annual sustaining capital expenditures. As the mine plan proceeds further from the existing crushing facility, haulage distance increases. This will require an increase in the haul truck fleet size in some years. Capital and operating costs were adjusted for this increased haulage requirement as shown in Appendix B. The fleet size is three trucks until 2027. From 2027 to 2036, from 2045 to 2052, and from 2100 to 2102 the fleet size is four trucks. From 2037 to 2044 and from 2053 to 2064 the fleet size is five trucks. From 2065 to 2067 the fleet size is six trucks. Tables 18.1 and 18.2 set for estimated capital costs and operating costs, respectively, used to estimate future operations for the TLC mine.

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18.1Capital Costs

Table 18.1 Capital Costs

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18.2Operating Costs

Table 18.2 Operating Costs

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19Economic Analysis

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The block model was used to estimate overburden and limestone ore volumes for each reserve area. Overburden mining is contracted out on a cost per bank cubic yard basis. Limestone volumes were converted to tons for cost and revenue estimation using a density factor of 155 pounds per cubic foot.

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The overburden thickness is generally uniform in each area. Northwest and East areas will have mining start where the limestone outcrops and the overburden is the thinnest or not present. This start method will allow TLC to develop the new areas at low initial stripping ratios. Thus the stripping ratio can be averaged annually across each reserve area. As mining develops mining equipment will be added.

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19.1Key Parameters and Assumptions

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The discount rate used in the economic analysis is 1.09%. This rate is TLC’s incremental borrowing cost. Per the current debt agreement and TLC’s current leverage ratio, TLC’s borrowing rate is 1.09% (calculated from the November 2021 LIBOR of 0.09%).

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The tax was estimated using TLC’s current effective income tax rate calculated on September 30, 2021. In reviewing the September 30, 2021 tax provision, the effective tax rate contained no material non-recurring permanent items that would influence the rate, so it is considered not applicable to future periods. Demand for limestone is projected to be approximately 1,400,000 tons per year for the life of the mine. The sales price per ton is estimated using the USGS Mineral Commodity Summaries 2021. Depreciation was estimated using existing assets and the approved items in the 2022 budget. The later years’ depreciations are calculated using the capital budget forecast and the asset life with a mid-year convention.

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19.2Economic Viability

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TLC has positive cash flow and the current mine plan does not require a significant capital expenditure until 2038; therefore, payback and return on investment calculations are irrelevant. NPV of the life of mine plan is $257.1 million. The annual cash flows are in Appendix B.

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19.3Sensitivity Analysis

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Sensitivity analysis was performed on the discount rate, contractor mining costs for stripping, contractor costs for limestone mining in the TLC East area, TLC mining costs, and all mining costs changing simultaneously.

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Table 19.3-1 Sensitivity Analysis: Varying Discount Rate

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Table 19.3-2 Sensitivity Analysis: Varying Limestone Mining Cost

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Table 19.3-3 Sensitivity Analysis: Varying TLC East Area Mining Cost

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Table 19.3-4 Sensitivity Analysis: Varying Contractor Stripping Cost

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Table 19.3-5 Sensitivity Analysis: Varying All Mining and Contract Mining and Stripping Costs

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Table 19.3-5 Sensitivity Analysis: Varying Limestone Price

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20Adjacent Properties

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Adjacent to the TLC property, there are many aggregate operations with quarries in the Edwards limestone. Some of these smaller privately owned operations have allowed the sampling or, in one instance, drilling on their property in exchange for the geologic data. The data the QP considered material to the geologic model was utilized for the resource estimate. The adjacent property data used was identified in Section 7.2 of this report.

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21Other Relevant Data and Information

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All data relevant to the supporting studies and estimates of mineral resources and reserves have been included in the sections of this TRS. No additional information or explanation is necessary to make this TRS understandable and not misleading.

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22Interpretation and Conclusions

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22.1 Interpretations and Conclusions

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Geologically, the deposit is a simple tabular, single bed limestone deposit with no structure and a shallow dip angle. The formation has been proven by regional, detailed local sampling, and drilling that the quality and thickness are very consistent. Because of this simple geology, the mining method is straightforward and consists of uncomplicated open pit mining.

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TLC has been in operation for many decades during varying economic and market conditions and the TLC plant has maintained a steady market share. The mining operation has been modernized over the last 25 years which has allowed it to optimize mining so that high grading is minimized. The economic analysis and amount of Proven and Probable Reserves indicate the operation reasonably has approximately 80 years of estimated mine life at current production levels.

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22.2 Risks and Uncertainties

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Internal to the mining operation, risks and uncertainties are minimal because of the uncomplicated geology and the employment of a standard mining method. Governmental, legal and regulatory risks, such as greenhouse gases, could adversely affect the market the TLC operation supplies.

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23Recommendations

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Recommended mining projects include: determining if there is an economic benefit to mining lower stripping ratio reserves sooner than projected and evaluating economic benefits versus the cost of reducing haulage time by moving the primary crusher and conveyor closer to the active mining areas.

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Development core drilling could be done in the northwest undeveloped area of the mine to prepare for mining in the future.

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24References

Brand JP. 1953. Cretaceous of Llano Estacado of Texas. BEG. TUTA. RI#20. 67 pgs.

Bureau of Economic Geology. 1992. Geology of Texas. SM 2. TUTA. 1 pg.

Bowers R, Vickers K, TerraCon. 1997. Resource Estimate. USLM Internal Report. 15 pgs.

Butler Dr. DR. 2021. Physical Regions of Texas. Texas Almanac Website. [Accessed 2021]. https://www.texasalmanac.com/articles/physical-regions

Cass C. 2021. Personal Communication. Firmatek LLC.

Collins EW. Baungardner Jr. RW. Geologic Map of the East Part of Cleburne Texas, 30 x 30 minute Quadrangle: South of Fort Worth-Interstate 35W Corridor. 2011. STATEMAP. NCGMP. BEG. TUTA. 1pg.

Digital Atlas of Ancient Life. Geology of the Western Interior Seaway. NSF DBI 1645520 [Accessed 2021]. https://www.cretaceousatlas.org/geology.

Dorsey. 2019. How will the new rules affect the definitions of mineral reserves, probable mineral reserves and proven mineral reserves? Understanding the SEC’s New Mining Disclosure Rules. [Accessed 2021]. https://www.dorsey.com/newsresources/publications/client-alerts/2019/02/new-mining-disclosure-rules-2019#:~:text=A%20proven%20mineral%20reserve%20is,tonnage%20and%20grade%20or%20quality.

Kyle, JR. 2018. Industrial Minerals of Texas (map). TEBG. 1 pg.

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Kyle J R, Elliot B H. 2019. Past, Present, and Future of Texas Industrial Minerals. M, M & E. 36:475–486.

Lewis, A A.1955. Investigation of limestone properties in Johnson and Hill Counties, Texas: Texas Lime Company Internal Report, 62 pgs.

Lewis, AA. 1958. Drill Hole Data Map Clyde McClung Property, Area No. 1: Texas Lime Company Internal map, scale 1 inch = 200 feet.

Lozo FE. et al. 1959. Symposium on Edwards Limestone in Central Texas. BEG. TUTA. P#5905. 40-42

Roberson DS. 1972. The Distribution and Significance of Circular Bioherms in the Edwards Limestone of Central Texas. BGS. BU. 40 pgs.

Swanson RG. 1981. Shell Sample Examination Manual. MIES1. AAPG. 102 pgs.

Texas Railroad Commission Website.2021. Chapter 3, Oil & Gas Division. [Accessed 2021]. ttps://texreg.sos.state.tx.us/public/readtac$ext.ViewTAC?tac_view=4&ti=16&pt=1&ch=3&rl=Y.

US Census.2020. Bureau of Quick Facts. USFG. [Accessed 2021]. https://www.census.gov/quickfacts.

USGS. 2021. MapView Website. [Accessed 2021]. https://ngmdb.usgs.gov/mapview/?center=-97,39.6&zoom=4.

US Geological Survey. 2021. Mineral Commodity Summaries 2021. Stone (Crushed). pg. 154. USGS. 200 pgs.

25Reliance on Information Provided by the Registrant

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The QP has relied upon information and data from TLC and USLM personnel and historical records in completing this TRS. This material included written reports and statements of other individuals and companies with whom it does business. The material also includes permits, licenses, historical exploration data, production records, equipment lists, geologic and ore body resource and reserve information, mine modeling data, financial data and summaries, mine equipment specifications and summaries, records, and equipment lists. The QP believes that the assumptions were factual and accurate and that the interpretations were reasonable. This material has been relied upon in the mine planning, capital and cost planning, and reviewed. The TLC mine engineer assisted the QP in reviewing these materials and performed the final reserve modeling and economic analysis under the direction of the QP. There is no reason to believe that any material facts have been withheld or misstated. In his professional judgment, the QP has taken all appropriate steps to ensure that the information or advice from TLC and USLM personnel and records and outside entities are accurate. The QP does not disclaim any responsibility for this Technical Report Summary.

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Appendix A: List of Data included in the Geologic Model

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Appendix B: Annual Cash Flow Analysis

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