phlogopite
/ˈfloʊɡəˌpaɪt/
noun
- A brown or yellow mica mineral that contains magnesium and is often found in metamorphic rocks.
- Geologists found phlogopite in the ancient rock layers of the mountain.
- Phlogopite is commonly used as an electrical insulator because it resists heat.
- The sparkling flakes in the stone were actually crystals of phlogopite.