Igneous Rocks:
* Granite: Biotite is a common constituent of granite, especially in the more mafic varieties like granodiorite.
* Diorite: Biotite is often found in diorite alongside other dark minerals like hornblende.
* Gabbro: Biotite can occur in gabbro, though it's less common than other minerals like pyroxene.
* Rhyolite: Biotite is found in some rhyolites, particularly those with a higher iron content.
Metamorphic Rocks:
* Schist: Biotite is a defining mineral of schist, often giving it a characteristic sheen.
* Gneiss: Biotite is often found in gneiss, especially in banded varieties where it forms dark layers.
* Marble: Biotite can be present in marble, particularly those derived from metamorphic limestone or dolostone.
Sedimentary Rocks:
* Sandstone: Biotite can be present in sandstone as a detrital mineral, particularly in those derived from weathered igneous or metamorphic rocks.
* Conglomerate: Biotite fragments can also be found in conglomerates, especially those containing clasts of igneous or metamorphic rocks.
Other Notable Locations:
* Pegmatites: Biotite is a common mineral in pegmatites, where it can form large crystals.
* Hydrothermal Deposits: Biotite can occur in hydrothermal deposits, especially those associated with volcanic activity.
Note: The specific occurrence and abundance of biotite will depend on factors like the rock's composition, formation conditions, and the presence of other minerals.
