4. Revenue Recognition (Details) - USD ($)	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Revenues	$ 2,432,929	$ 2,619,330
Antimony
Revenues	1,681,812	1,986,507
Zeolite
Revenues	690,707	612,012
Precious metals
Revenues	60,410	20,811
United States
Revenues	2,099,521	2,297,055
Canada
Revenues	185,238	322,275
Mexico
Revenues	$ 148,170	$ 0