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SHAREHOLDERS' EQUITY (Details) $ / shares in Units, $ in Millions |  |  |  |  |  | 3 Months Ended | 6 Months Ended |  |
--- | --- | --- | --- | --- | --- | --- | --- | --- | ---
May 23, 2019 USD ($) shares | Mar. 29, 2019 USD ($) $ / shares shares | Dec. 20, 2018 CAD ($) | Dec. 20, 2018 USD ($) $ / shares shares | Nov. 08, 2018 USD ($) | Dec. 19, 2017 CAD ($) | Dec. 19, 2017 USD ($) $ / shares shares | Jun. 30, 2019 USD ($) shares | Mar. 31, 2019 USD ($) shares | Jun. 30, 2018 USD ($) shares | Jun. 30, 2019 CAD ($) shares | Jun. 30, 2019 USD ($) $ / shares shares | Jun. 30, 2018 CAD ($) shares | Jun. 30, 2018 USD ($) $ / shares shares | Dec. 31, 2018 USD ($) shares | Jun. 11, 2018 shares
Shareholders' distributions |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 1,686,000 |  |
Semi-annual shareholders' distribution | $ / shares |  |  |  |  |  |  |  |  |  |  |  |  |  | 0.005 |  |
Common stock issued | shares |  |  |  |  |  |  |  | 361,957,000 |  |  |  | 361,957,000 |  |  | 344,560,000 |
Weighted average exercise price of stock options (in dollars per share) | $ / shares |  |  |  |  |  |  |  |  |  |  |  | $ 1.01 |  | $ 1.14 |  |
Shares of common stock issued upon exercise of stock options | shares |  |  |  |  |  |  |  |  |  |  | 257,500 | 257,500 | 39,199 | 39,199 |  |
Exercise of stock options |  |  |  |  |  |  |  | $ 37,000 |  | $ 5,000 |  | $ 260,000 |  | $ 45,000 |  |
Proceeds from exercise of stock options |  |  |  |  |  |  |  |  |  |  |  | 260,000 |  | 45,000 |  |
Stock-based compensation |  |  |  |  |  |  |  | 136,000 |  | 193,000 |  | 197,000 |  | 396,000 |  |
Stock options granted |  |  |  |  |  |  |  |  |  |  |  | 2,600,000 |  |  |  |
Restricted cash |  |  |  |  |  |  |  | 13,112,000 |  |  |  | 13,112,000 |  |  | $ 14,685,000 |
Number of units issued | shares | 1,935,484 | 14,193,548 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Price per unit | $ / shares |  | $ 1.55 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Net proceeds |  | $ 20,300,000 |  |  |  |  |  |  |  |  |  | 22,900,000 |  |  |  |
Issuance costs | $ 300,000 | $ 1,700,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Flow-through share premium received |  |  |  |  |  |  |  | 2,344,000 |  |  |  | 2,344,000 |  |  | 2,950,000 |
Number of warrants received for each share of common stock share sold | shares |  | 0.50 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of common share per warrant | shares |  | 1 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Outstanding warrants |  |  |  |  |  |  |  | 8,064,516 |  | $ 10,350,000 |  | 8,064,516 |  | 10,350,000 |  |
Warrants issued in connection with registered direct offering (note 8) |  |  |  |  |  |  |  | $ 2,634,000 |  |  |  | $ 2,634,000 |  |  |  |
Black Fox |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Common stock issued | shares |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 178,321
Maximum |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Proceeds from exercise of stock options |  |  |  |  |  |  |  |  |  |  |  |  |  | 100,000 |  |
Officers, directors and certain employees |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Weighted average exercise price of stock options (in dollars per share) | $ / shares |  |  |  |  |  |  |  |  |  |  |  | $ 1.67 |  |  |  |
Common Stock |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Shareholders' distributions |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 1,686,000 |  |
Shares of common stock issued upon exercise of stock options | shares |  |  |  |  |  |  |  | 36,000 |  | 4,000 | 258,000 | 258,000 | 39,000 | 39,000 |  |
Exercise of stock options |  |  |  |  |  |  |  | $ 37,000 |  | $ 5,000 |  | $ 260,000 |  | $ 45,000 |  |
Stock-based compensation |  |  |  |  |  |  |  | 136,000 |  | $ 193,000 |  | 197,000 |  | $ 396,000 |  |
Net proceeds |  |  |  |  |  |  |  |  |  |  |  | 20,300,000 |  |  |  |
Shares of common stock issued as payment for mining concessions in Mexico | shares |  |  |  |  |  |  |  |  |  | 178,000 |  |  | 178,000 | 178,000 |  |
Warrants |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Net proceeds |  |  |  |  |  |  |  |  |  |  |  | 2,600,000 |  |  |  |
Number of common share per warrant | shares |  | 1 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Price per common share for each warrant | $ / shares |  | $ 2.00 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Warrants Expiration Term |  | 3 years |  |  |  |  |  |  |  |  |  |  |  |  |  |
Subscription Receipts |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of units issued | shares |  | 1,935,484 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Price per unit | $ / shares |  | $ 1.55 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Net proceeds | $ 2,600,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of units received upon necessary shareholder and NYSE approvals | shares |  | 1 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Flow Through Common Shares |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Common stock issued | shares |  |  |  | 6,634,000 |  |  | 4,000,000 |  |  |  |  |  |  |  |  |
Restricted cash for exploration activities |  |  |  |  |  |  |  |  |  |  | $ 17.1 | 13,100,000 |  |  |  |
Price per unit | $ / shares |  |  |  | $ 2.24 |  |  | $ 2.50 |  |  |  |  |  |  |  |  |
Net proceeds |  |  | $ 20.0 | $ 14,900,000 |  | $ 12.9 | $ 10,000,000.0 |  |  |  |  |  |  |  |  |
Flow-through share premium received |  |  |  |  |  |  |  |  |  | $ 3,000,000.0 |  |  |  | $ 3,000,000.0 | $ 11,900,000 |
Flow-through share recovery of premium |  |  |  |  |  |  |  | $ 600,000 |  | $ 1,300,000 |  | 600,000 |  | 1,300,000 |  |
Flow through expenditure incurred |  |  |  |  |  |  |  |  |  |  | $ 4.6 | 3,500,000 | $ 10.5 | $ 8,100,000 |  |
ATM offering |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Common stock issued | shares |  |  |  |  |  |  |  |  | 1,010,545 |  |  |  |  |  |  |
Sale of common stock for cash, net of issuance costs |  |  |  |  |  |  |  |  |  |  |  | 1,851,000 |  |  |  |
Aggregate offering price |  |  |  |  | $ 90,000,000.0 |  |  |  |  |  |  |  |  |  |  |
Net proceeds |  |  |  |  |  |  |  |  | $ 1,900,000 |  |  | $ 1,851,000 |  |  |  |
ATM offering | Common Stock |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of units issued | shares |  |  |  |  |  |  |  |  |  |  | 1,010,000 | 1,010,000 |  |  |  |
Net proceeds |  |  |  |  |  |  |  |  |  |  |  | $ 1,851,000 |  |  |  |

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