Sandfire Resources (ASX:SFR) struck more high-grade copper at the Black Butte project in Montana, US after drilling 32 holes, according to a Thursday filing with the Australian bourse.

Results include 3.2 meters at roughly 20% copper, 2.8 meters at about 9% copper, and 2.8 meters at nearly 12% copper from the Johnny Lee Lower Copper Zone, the filing said. Drilling is ongoing to expand the zone's resources.

Sandfire has an 87% equity stake in the Toronto Stock Exchange-listed Sandfire Resources America, which owns 100% of the Black Butte project.

The mining company's shares were down past 3% in recent Thursday trade.

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