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SHAREHOLDERS' EQUITY (Details) - USD ($) $ / shares in Units, $ in Thousands |  |  |  |  | 3 Months Ended | 9 Months Ended
--- | --- | --- | --- | --- | --- | ---
Sep. 10, 2020 | May 23, 2019 | Mar. 29, 2019 | Nov. 08, 2018 | Sep. 30, 2020 | Jun. 30, 2020 | Sep. 30, 2019 | Mar. 31, 2019 | Sep. 30, 2020 | Sep. 30, 2019
Number of units issued |  | 1,935,484 | 14,193,548 |  |  |  |  |  |  |
Price per unit |  |  | $ 1.55 |  |  |  |  |  |  |
Net proceeds |  | $ 2,600 | $ 20,300 |  |  |  |  |  |  |
Issuance costs |  | $ 400 | $ 1,700 |  |  |  |  |  |  |
Flow-through share premium received |  |  |  |  | $ 2,058 |  |  |  | $ 2,058 |
Number of shares of common stock |  |  | 1 |  |  |  |  |  |  |
Number of warrants received for each share of common stock share sold |  |  | 0.5 |  |  |  |  |  |  |
Sale of common stock for cash, net of issuance costs |  |  |  |  |  |  |  |  |  | $ 22,910
Shares of common stock issued upon exercise of stock options |  |  |  |  |  |  |  |  | 60,000 | 405,000
Proceeds from exercise of stock options |  |  |  |  |  |  |  |  | $ 61 | $ 411
Weighted average exercise price of stock options (in dollars per share) |  |  |  |  |  |  |  |  | $ 1.06 | $ 1.01
Stock-based compensation |  |  |  |  | $ 300 |  | $ 300 |  | $ 332 | $ 481
Shares issued for acquisition of mineral property interests (in shares) |  |  |  |  | 53,600 |  |  |  |  |
Officers, directors and certain employees |  |  |  |  |  |  |  |  |  |
Weighted average exercise price of stock options (in dollars per share) |  |  |  |  | $ 1.25 |  |  |  |  |
Stock options granted (in shares) |  |  |  |  | 4,796,550 |  |  |  |  |
June 2020 Amended and Restated Credit Agreement |  |  |  |  |  |  |  |  |  |
Number of units issued |  |  |  |  |  | 2,091,700 |  |  |  |
Net proceeds |  |  |  |  |  | $ 1,900 |  |  |  |
Common Stock and Additional Paid-in Capital |  |  |  |  |  |  |  |  |  |
Shares of common stock issued upon exercise of stock options |  |  |  |  |  |  | 147,000 |  | 60,000 | 405,000
Shares issued for acquisition of mineral property interests (in shares) |  |  |  |  | 53,000 |  | 354,000 |  | 53,000 | 354,000
Warrants |  |  |  |  |  |  |  |  |  |
Number of shares of common stock |  |  | 1 |  |  |  |  |  |  |
Price per common share for each warrant |  |  | $ 2.00 |  |  |  |  |  |  |
Warrant expiration term |  |  | 3 years |  |  |  |  |  |  |
Subscription Receipts | Officers, directors and certain employees |  |  |  |  |  |  |  |  |  |
Number of units issued |  |  | 1,935,484 |  |  |  |  |  |  |
Price per unit |  |  | $ 1.55 |  |  |  |  |  |  |
Flow Through Common Shares |  |  |  |  |  |  |  |  |  |
Number of units issued | 6,298,166 |  |  |  |  |  |  |  |  |
Price per unit | $ 1.65 |  |  |  |  |  |  |  |  |
Net proceeds | $ 9,800 |  |  |  |  |  |  |  |  |
Net proceeds allocated to the sale of tax benefits | 2,000 |  |  |  |  |  |  |  |  |
Issuance costs | 600 |  |  |  |  |  |  |  |  |
Gross proceeds | 10,400 |  |  |  |  |  |  |  |  |
Sale of common stock for cash, net of issuance costs | $ 7,800 |  |  |  |  |  |  |  |  |
ATM offering |  |  |  |  |  |  |  |  |  |
Number of units issued |  |  |  |  |  |  |  | 1,010,545 |  |
Net proceeds |  |  |  |  |  |  |  |  |  | $ 1,851
Aggregate offering price |  |  |  | $ 90,000 |  |  |  |  |  |
Sale of common stock for cash, net of issuance costs |  |  |  |  |  |  |  | $ 1,900 |  |
ATM offering | Common Stock and Additional Paid-in Capital |  |  |  |  |  |  |  |  |  |
Number of units issued |  |  |  |  |  |  |  |  |  | 1,010,000
Net proceeds |  |  |  |  |  |  |  |  |  | $ 1,851

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