Assertion: biotite | /r/AtLocation | many pegmatite masses
Facets:
Source sentences:
text: The more important occurrences follow: Biotite occurs in many igneous rocks (e.g., granites and granodiorites), is common in many pegmatite masses, and constitutes one of the chief components of many metamorphic rocks (e.g., gneisses, schists, and hornfelses).