Skip to main content
U.S. flag

An official website of the United States government

Biotitic Mafic Dike at the Blackbird Cobalt-Copper Mine

Detailed Description

USGS scientist John Slack holds his hammer to a biotitic mafic dike, intruded into twice-folded banded siltite, exposed in the Hawkeye adit of the Blackbird cobalt-copper mine, in the Salmon River Mountains of east-central Idaho. Biotite is a type of mica, and mafic refers to a high magnesium and iron content.


Public Domain.