| Schedule of Property, Plant and Equipment, Net |
Depreciation is computed using the straight-line method over estimated useful lives as follows: | | | | | | | Building | 7 to 15 years | | Vehicles and equipment | 3 to 7 years | | Processing and laboratory | 5 to 15 years | | Furniture and fixtures | 2 to 3 years |
Properties, plant and equipment at December 31, 2021 and 2020, respectively, include the following: | | | | | | | | | | | | | December 31, 2021 | | December 31, 2020 | | Land | $ | 6,328,338 | | | $ | — | | | Real property leased to third parties | 3,298,311 | | | 3,298,311 | | | Property, plant and equipment for mineral processing | 27,644,745 | | | 27,644,744 | | | Other property and equipment | 4,438,657 | | | 4,367,229 | | | Accumulated depreciation | (27,146,379) | | | (26,685,584) | | | Total property, plant and equipment, net | $ | 14,563,672 | | | $ | 8,624,700 | |
Properties, plant and equipment at March 31, 2022 and December 31, 2021, respectively, include the following: | | | | | | | | | | | | | | March 31, 2022 | | December 31, 2021 | | Land | $ | 6,328,338 | | | $ | 6,328,338 | | | Real property leased to third parties | 3,298,312 | | | 3,298,311 | | | Property, plant and equipment for mineral processing | 27,644,745 | | | 27,644,745 | | | Other property and equipment | 5,221,158 | | | 4,438,657 | | | Accumulated depreciation | (27,284,196) | | | (27,146,379) | | | Total property, plant and equipment, net | $ | 15,208,357 | | | $ | 14,563,672 | |
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