gossan
/ˈɡɑsən/
noun
- A rust-colored, iron-rich rock that forms on the surface of a mineral deposit, often indicating the presence of valuable metals below.
- Geologists studied the gossan to decide where to drill for silver.
- The trail led through a patch of bright orange gossan, a clue to the old mine nearby.
- The miners recognized the reddish gossan as a sign that copper might be underneath.
Synonyms