4. PROPERTY, PLANT AND EQUIPMENT, NET (Tables)

12 Months Ended

Dec. 31, 2020

Property, Plant and Equipment [Abstract]

Property, plant and equipment, net

	December 31, 2020			December 31, 2019
At cost:
Mineral rights	$	2,955,780		$	2,764,462
Buildings		64,024,667			59,880,567
Plant and machinery		258,400,710			234,669,007
Motor vehicles		6,553			6,129
Furniture, fixtures and office equipment		3,318,564			3,235,736
Construction in process		12,095,565			1,204,742
Total		340,801,839			301,760,643
Less: Accumulated depreciation and amortization		(173,212,554	)		(146,330,705	)
Impairment		(18,641,596	)		(17,434,989	)
Net book value	$	148,947,689		$	137,994,949