noun
- a dark-colored mica mineral containing iron and magnesium, commonly found in igneous and metamorphic rocks
Usage: geology
Examples
- The granite sample contained large flakes of biotite that gave it a speckled appearance.
- Biotite is easily identified by its dark color and perfect cleavage.
- The metamorphic rock showed bands of quartz alternating with biotite-rich layers.
- Geologists use biotite crystals to determine the age of igneous rocks.
- The biotite in the schist had a distinctive bronze-colored luster.
- Under the microscope, biotite appears as thin, dark sheets.