13. INCOME TAXES (Details 2) - USD ($)	Mar. 31, 2021	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Deferred tax liabilities	$ 0	$ 0
Deferred tax assets:
Impairment on property, plant and equipment	2,712,092	2,907,548
Impairment on prepaid land lease	877,656	883,884
Exploration costs	1,894,641	1,908,087
Compensation costs of unexercised stock options	72,699	74,883
PRC tax losses	22,296,935	21,643,028
US federal net operating loss	1,063,644	1,045,503
Total deferred tax assets	28,917,667	28,462,933
Valuation allowance	(9,785,742)	(9,872,706)
Net deferred tax asset	$ 19,131,925	$ 18,590,227