Note 12 - Fair Value Measurement (Tables)

3 Months Ended

Mar. 31, 2019

Notes Tables

Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block]

Description	Balance at March 31, 2019		Balance at December 31, 2018		Input Hierarchy Level
Assets:
Cash and cash equivalents:
Money market funds and other bank deposits	$	11,797	$	27,389	Level 1
Available for sale securities:
Equity securities – mining industry		6,768		6,583	Level 1
Trade accounts receivable:
Receivables from provisional concentrate sales		9,586		4,184	Level 2
Restricted cash balances:
Certificates of deposit and other bank deposits		1,025		1,025	Level 1
Derivative contracts:
Metal forward contracts		207		209	Level 2
Foreign exchange contracts		153		23	Level 2
Total assets	$	29,536	$	39,413
Liabilities:
Derivative contracts:
Metal forward contracts	$	4,057	$	373	Level 2
Foreign exchange contracts		4,649		8,595	Level 2
Total Liabilities	$	8,706	$	8,968