greisen
/ˈɡraɪzən/
noun
- A type of rock that forms when granite is changed by hot gases and liquids, often containing valuable minerals like tin or tungsten.
- Geologists study greisen to understand how mineral deposits form in the earth.
- The miners discovered a rich vein of tin in the greisen deposit.
- The old quarry exposed a large area of greisen with visible crystals.