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PLANT AND EQUIPMENT AND MINERAL PROPERTIES (Narrative) (Details) - USD ($)		12 Months Ended
	May 27, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Abandonment of mineral properties		$ 287,000	$ 1,036,000	$ 2,770,000
Nichols Ranch
Property, Plant and Equipment [Line Items]
Depreciation		$ 3,170,000	$ 4,430,000	$ 2,370,000.00
Roca Honda
Property, Plant and Equipment [Line Items]
Number of shares issued (in shares)	1,212,173
Percentage of voting interests acquired	40.00%
Value assigned of equity interest issued	$ 2,630,000
Cash payable	$ 4,500,000