US Copper Announces Positive Drill Results at Moonlight Deposit
US Copper has announced encouraging results from a 15-hole shallow drill program conducted last fall on its Moonlight deposit, part of the Moonlight-Superior Copper Project in North-East California.
The drill program revealed that 14 out of 15 holes contained acid soluble copper, including one intercept with 205 feet of 0.644% recoverable copper. These results confirm the presence of a small oxide cap over the larger Moonlight sulfide deposit, previously considered waste rock by former operators. The soluble copper averaged 91% of total copper, with concentrations greater than 0.2% extending over an area of 2,000 by 1,500 feet to an average depth of more than 150 feet.
An independent engineering firm is currently reviewing the results to determine parameters for further metallurgical testing, a new resource calculation for the oxide mineralization, and the economic viability of an oxide mining operation that combines the Engels and Moonlight oxide caps.
Stephen Dunn, President and CEO of US Copper, commented on the findings, highlighting the potential economic benefits of copper oxide deposits. These deposits can typically be extracted through low-impact surface mining and processed at lower costs compared to copper sulfide ores. He also noted the strategic importance of advancing a secure domestic supply of U.S.-mined copper, especially with copper recently added to the U.S. critical minerals list.
The Moonlight deposit primarily consists of copper sulfide minerals hosted in the Lights Creek stock of Quartz Monzonite. It features both disseminated sulfide minerals and structurally controlled mineralization with tourmaline vein and breccia structures. The small oxide cap, mainly malachite with some chalcocite and native copper, covers the deposit surface. Historical estimates by Placer-Amex in the 1970s indicated a resource of 12.2 million tons at 0.54% copper for the oxide cap, though this estimate is not currently reliable.
The current National Instrument 43-101 (NI 43-101) resource estimate for the Moonlight sulfide deposit includes an indicated resource of approximately 252 million tons averaging 0.25% copper and 0.07 oz/silver per ton, and an inferred resource of 109 million tons averaging 0.24% copper and 0.08 oz/silver per ton. The indicated resources contain 1.272 billion pounds of copper and 18 million ounces of silver, while the inferred resources contain 534 million pounds of copper and 9 million ounces of silver. The deposit remains open to the south and at depth.
A Preliminary Economic Assessment (PEA) for the Moonlight deposit, prepared by Tetra Tech in 2018, demonstrated positive economics at $3.15 per pound of copper. The integration of higher-grade ore from the Superior and Engels deposits could potentially enhance the project's economics by increasing cash flows in the initial years of production. Recent drilling at these deposits aims to better define higher-grade ore for potential starter pits to supply the Moonlight plant, ultimately leading to an updated PEA.
