13. INCOME TAXES (Details 2) - USD ($)	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Deferred tax liabilities	$ 0	$ 0
Deferred tax assets:
Allowance for obsolete and slow-moving inventories	10,980	0
Impairment on property, plant and equipment	4,610,228	421,105
Exploration costs	1,905,347	1,794,667
Compensation costs of unexercised stock options	98,092	120,986
US federal net operating loss	7,080,000	11,575,000
Total deferred tax assets	13,704,647	13,911,758
Valuation allowance	(7,178,092)	(11,695,986)
Net deferred tax asset	6,526,555	2,215,772
Current deferred tax asset	0	0
Long-term deferred tax asset	$ 6,526,555	$ 2,215,772

Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences and carryforwards.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible domestic operating loss carryforwards. Excludes state and local operating loss carryforwards.

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Amount, before allocation of valuation allowance, of deferred tax asset attributable to deductible temporary differences from reserves and accruals, classified as other.

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Amount of deferred tax assets for which it is more likely than not that a tax benefit will not be realized.

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