Note 11 - Derivative Instruments (Tables)

6 Months Ended

Jun. 30, 2018

Notes Tables

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

June 30, 2018	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
2018 settlements		1,114		5		20,889		4,960	$	16.50	$	1,298	$	1.38	$	1.07
Contracts on forecasted sales
2018 settlements		—		—		9,039		5,787		N/A		N/A	$	1.34	$	1.09
2019 settlements		—		—		48,502		20,283		N/A		N/A	$	1.40	$	1.10
2020 settlements		—		—		42,329		19,401		N/A		N/A	$	1.40	$	1.13
2021 settlements		—		—		—		4,409		N/A		N/A		N/A	$	1.07

December 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
2018 settlements		1,447		5		21,550		4,740	$	16.64	$	1,279	$	1.45	$	1.11
Contracts on forecasted sales
2018 settlements		—		—		32,187		16,645		N/A		N/A	$	1.29	$	1.06
2019 settlements		—		—		23,589		18,078		N/A		N/A	$	1.33	$	1.09
2020 settlements		—		—		3,307		2,866		N/A		N/A	$	1.27	$	1.08