actinolite
/ækˈtɪnəlaɪt/
noun
- A greenish mineral of the amphibole group, often found in metamorphic rocks.
- The green streaks in the stone were caused by actinolite.
- Actinolite is sometimes used as a gemstone when it forms long, fibrous crystals.
- Geologists found actinolite in the mountain's metamorphic rock layers.