Note 11 - Derivative Instruments (Tables)

3 Months Ended

Mar. 31, 2017

Notes Tables

Schedule of Notional Amounts of Outstanding Derivative Positions [Table Text Block]

March 31, 2017	Ounces/pounds under contract (in 000's)								Average price per ounce/pound
	Silver		Gold		Zinc		Lead		Silver		Gold		Zinc		Lead
	(ounces)		(ounces)		(pounds)		(pounds)		(ounces)		(ounces)		(pounds)		(pounds)
Contracts on provisional sales
2017 settlements		1,455		6		20,999		4,079	$	18.10	$	1,245	$	1.27	$	1.03
Contracts on forecasted sales
2017 settlements		—		—		17,527		11,133		N/A		N/A	$	1.23	$	1.05
2018 settlements		—		—		20,613		9,700		N/A		N/A	$	1.23	$	1.06
2019 settlements		—		—		1,102		—		N/A		N/A	$	1.21		N/A

December 31, 2016	Ounces/pounds under contract (in 000's)								Average price per ounce/pound
	Silver		Gold		Zinc		Lead		Silver		Gold		Zinc		Lead
	(ounces)		(ounces)		(pounds)		(pounds)		(ounces)		(ounces)		(pounds)		(pounds)
Contracts on provisional sales
2017 settlements		1,295		4		19,070		7,441	$	16.29	$	1,172	$	1.18	$	0.97
Contracts on forecasted sales
2017 settlements		—		—		35,384		17,637		N/A		N/A	$	1.19	$	1.03
2018 settlements		—		—		13,779		5,732		N/A		N/A	$	1.21	$	1.05