| In millions, except per share items | Mar-05-23 | Dec-31-22 | Sep-30-22 | Jun-30-22 | Mar-31-22 | Mar-05-22 | Dec-31-21 | Sep-30-21 |
| | 8-K | 10-Q | S-1/A | 10-K | 10-Q | 8-K | 10-Q | S-1/A |
| Cash Flows From Operating Activities: | | | | | | | | |
| Net income (loss) | | -14.9 | 4.6 | -13.2 | -33.0 | | -11.0 | -9.5 |
| Adjustments to reconcile net income (loss) to net cash used by operating activities: | | | | | | | | |
| Depreciation and amortization | | 0.0 | 0.0 | 0.0 | | | 0.0 | 0.0 |
| Share based compensation | | 2.2 | 1.3 | 2.3 | | | 1.3 | 1.8 |
| Common stock issued for consulting fees | | | | 3.9 | | | 1.9 | 1.5 |
| Unrealized (gain) loss on convertible note derivative instrument | | 2.2 | -13.9 | | | | | |
| Accretion of reclamation liability | | 0.0 | 0.0 | 0.0 | | | 0.0 | 0.0 |
| Amortization of debt issuance costs and discount - convertible note | | 2.0 | | | | | | |
| Amortization of right of use asset | | 0.0 | 0.0 | | | | | |
| Interest earned on reclamation bond | | | | 0.0 | | | 0.0 | |
| Net foreign exchange (gain) loss | | | | -0.1 | | | 0.2 | -1.2 |
| Change in: | | | | | | | | |
| Prepaid expenses and other current assets | | 0.5 | 0.0 | 1.7 | | | -0.3 | 0.0 |
| Accounts payable and accrued liabilities | | 0.1 | -0.4 | 0.1 | | | -0.1 | 2.5 |
| Net cash used in operating activities | | -8.4 | -7.8 | -5.2 | -33.0 | | -8.0 | -4.8 |
| |
| Cash Flows From Investing Activities: | | | | | | | | |
| Construction in progress | | | | | | | | |
| Mineral rights and properties additions | | | | | | | | |
| Properties, plant and equipment additions | | -0.2 | 0.0 | 0.0 | | | -0.2 | -0.9 |
| Net cash used in investing activities | | -11.0 | -5.1 | -6.8 | | | -0.9 | -1.9 |
| |
| Cash Flows From Financing Activities: | | | | | | | | |
| Proceeds from issuance of convertible note | | | 55.8 | | | | | |
| Payments on note payable | | 0.0 | 0.0 | 0.0 | | | | 0.0 |
| Proceeds from issuance of common stock | | | | 0.0 | | | 26.3 | |
| Share offering costs | | | | 0.0 | | | -0.8 | |
| Proceeds from exercise of stock options | | 1.9 | 0.3 | 2.1 | | | 1.8 | 1.1 |
| Net cash provided by financing activities | | 1.9 | 56.1 | 2.1 | | | 27.3 | 1.1 |
| Net increase (decrease) in cash and cash equivalents | | -17.5 | 43.1 | -9.4 | | | 18.5 | -5.7 |
| Effect of exchange rate fluctuation on cash | | | | -0.2 | | | 0.6 | -0.4 |
| |
| Supplemental Disclosure of Cash Flow Information: | | | | | | | | |
| Cash paid for interest | | 0.0 | 0.0 | | | | | |
| Noncash Investing and Financing Activities: | | | | | | | | |
| Accounts payable and accrued liabilities change related to construction in progress | | 5.4 | | | | | 0.8 | |
| Construction in progress transferred to properties, plant and equipment | | | | 0.0 | | | 0.1 | |
| Equipment acquired with notes payable | | | | | | | 0.2 | |
| Recognition of operating lease liabilities and right of use assets | | | | 0.1 | | | 0.0 | |
| Increase (decrease) in asset retirement costs | | 0.2 | | | | | | |