igneous
Biotite-bearing granite
Granite, composed mainly of quartz, feldspar, and biotite mica
AI-generated identification · may be incorrectCoarse-grained, mottled pink, gray, and black; visible interlocking crystals with a glassy-to-dull luster. Quartz and feldspar are about Mohs 6–7; biotite is about 2.5–3, with sheet cleavage.
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Physical properties
Coarse-grained, mottled pink, gray, and black; visible interlocking crystals with a glassy-to-dull luster. Quartz and feldspar are about Mohs 6–7; biotite is about 2.5–3, with sheet cleavage.
Formation & geological history
Formed when silica-rich magma cooled slowly underground, allowing large crystals to grow; typically Precambrian to recent in age, depending on locality.
Uses & applications
Used as dimension stone, paving, countertops, monuments, and decorative aggregate; generally not used as a gemstone.
Geological facts
The dark flakes are likely biotite, while pink areas commonly indicate potassium feldspar; the image alone cannot confirm the exact mineral proportions.
Field identification & locations
Look for coarse, interlocking quartz and feldspar with dark mica flakes and no layering. Granite is widespread in continental crust and exposed in mountain ranges and shield regions.
