v3.26.1
Property, plant and equipment - Disclosure of property, plant and equipment (Details) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2025
Dec. 31, 2024
Disclosure of detailed information about property, plant and equipment [Line items]    
Balance at beginning $ 147,399  
Impairment for the year 10,400 $ 0
Balance at end 248,815 147,399
Cost [Member]    
Disclosure of detailed information about property, plant and equipment [Line items]    
Balance at beginning 397,827 379,438
Asset additions 134,095 19,809
Asset disposals (31)  
Change in decommissioning provision (1,014) (1,420)
Balance at end 530,877 397,827
Accumulated depreciation and depletion [Member]    
Disclosure of detailed information about property, plant and equipment [Line items]    
Balance at beginning (250,428) (226,337)
Depreciation/depletion for the year (21,234) (24,091)
Impairment for the year (10,400)  
Balance at end (282,062) (250,428)
Mining interests [Member]    
Disclosure of detailed information about property, plant and equipment [Line items]    
Balance at beginning 92,979  
Balance at end 192,384 92,979
Mining interests [Member] | Cost [Member]    
Disclosure of detailed information about property, plant and equipment [Line items]    
Balance at beginning 239,625 226,819
Asset additions 111,652 14,226
Asset disposals 0  
Change in decommissioning provision (1,014) (1,420)
Balance at end 350,263 239,625
Mining interests [Member] | Accumulated depreciation and depletion [Member]    
Disclosure of detailed information about property, plant and equipment [Line items]    
Balance at beginning (146,646) (132,474)
Depreciation/depletion for the year (11,233) (14,172)
Impairment for the year 0  
Balance at end (157,879) (146,646)
Non-producing properties [Member]    
Disclosure of detailed information about property, plant and equipment [Line items]    
Balance at beginning 12,469  
Balance at end 12,469 12,469
Non-producing properties [Member] | Cost [Member]    
Disclosure of detailed information about property, plant and equipment [Line items]    
Balance at beginning 12,469 12,469
Asset additions 0 0
Asset disposals 0  
Change in decommissioning provision 0 0
Balance at end 12,469 12,469
Non-producing properties [Member] | Accumulated depreciation and depletion [Member]    
Disclosure of detailed information about property, plant and equipment [Line items]    
Balance at beginning 0 0
Depreciation/depletion for the year 0 0
Impairment for the year 0  
Balance at end 0 0
Plant and equipment [Member]    
Disclosure of detailed information about property, plant and equipment [Line items]    
Balance at beginning 38,967  
Balance at end 40,028 38,967
Plant and equipment [Member] | Cost [Member]    
Disclosure of detailed information about property, plant and equipment [Line items]    
Balance at beginning 133,022 128,228
Asset additions 19,202 4,794
Asset disposals 0  
Change in decommissioning provision 0 0
Balance at end 152,224 133,022
Plant and equipment [Member] | Accumulated depreciation and depletion [Member]    
Disclosure of detailed information about property, plant and equipment [Line items]    
Balance at beginning (94,055) (85,440)
Depreciation/depletion for the year (7,741) (8,615)
Impairment for the year (10,400)  
Balance at end (112,196) (94,055)
Right-of-use lease assets [Member]    
Disclosure of detailed information about property, plant and equipment [Line items]    
Balance at beginning 2,973  
Balance at end 3,626 2,973
Right-of-use lease assets [Member] | Cost [Member]    
Disclosure of detailed information about property, plant and equipment [Line items]    
Balance at beginning 12,474 11,685
Asset additions 2,933 789
Asset disposals (31)  
Change in decommissioning provision 0 0
Balance at end 15,376 12,474
Right-of-use lease assets [Member] | Accumulated depreciation and depletion [Member]    
Disclosure of detailed information about property, plant and equipment [Line items]    
Balance at beginning (9,501) (8,223)
Depreciation/depletion for the year (2,249) (1,278)
Impairment for the year 0  
Balance at end (11,750) (9,501)
Corporate office equipment [Member]    
Disclosure of detailed information about property, plant and equipment [Line items]    
Balance at beginning 11  
Balance at end 308 11
Corporate office equipment [Member] | Cost [Member]    
Disclosure of detailed information about property, plant and equipment [Line items]    
Balance at beginning 237 237
Asset additions 308 0
Asset disposals 0  
Change in decommissioning provision 0 0
Balance at end 545 237
Corporate office equipment [Member] | Accumulated depreciation and depletion [Member]    
Disclosure of detailed information about property, plant and equipment [Line items]    
Balance at beginning (226) (200)
Depreciation/depletion for the year (11) (26)
Impairment for the year 0  
Balance at end $ (237) $ (226)