4. PROPERTY, PLANT AND EQUIPMENT, NET (Details) - USD ($)	3 Months Ended	12 Months Ended
Mar. 31, 2021	Dec. 31, 2020
Property, Plant and Equipment [Abstract]
Mineral rights	$ 2,934,951	$ 2,955,780
Buildings	63,573,495	64,024,667
Plant and machinery	256,579,799	258,400,710
Motor vehicles	6,507	6,553
Furniture, fixtures and office equipment	3,295,179	3,318,564
Construction in progress	18,127,541	12,095,565
Total	344,517,472	340,801,839
Less: accumulated depreciation and amortization	(176,040,608)	(173,212,554)
Impairment	(18,510,233)	(18,641,596)
Net book value	$ 149,966,631	$ 148,947,689

Vehicles Gross

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- Definition

Amount of accumulated depreciation, depletion and amortization for physical assets used in the normal conduct of business to produce goods and services.

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- Definition

Amount before accumulated depreciation of building structures held for productive use including addition, improvement, or renovation to the structure, including, but not limited to, interior masonry, interior flooring, electrical, and plumbing.

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Amount of structure or a modification to a structure under construction. Includes recently completed structures or modifications to structures that have not been placed into service.

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Amount before accumulated depreciation of equipment commonly used in offices and stores that have no permanent connection to the structure of a building or utilities. Examples include, but are not limited to, desks, chairs, tables, and bookcases.

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Carrying amount at the balance sheet date of mineral properties, gross of adjustments.

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Amount before accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

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Amount after accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business to produce goods and services and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

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Amount before accumulated depreciation, depletion and amortization of other physical assets used in the normal conduct of business to produce goods and services and not intended for resale.

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The charge against earnings resulting from the aggregate write down of tangible assets from their carrying value to their fair value.

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