igneous
Weathered granite (likely biotite granite)
Granite; interlocking quartz, feldspar, and mica, commonly with biotite
AI-generated identification · may be incorrectTypically Mohs 6–7; coarse-grained, pink-gray to brown, with a glassy quartz luster and dull feldspar/mica surfaces. The specimen shows weathering and iron-oxide staining; exact mineral proportions are uncertain from the image.
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Physical properties
Typically Mohs 6–7; coarse-grained, pink-gray to brown, with a glassy quartz luster and dull feldspar/mica surfaces. The specimen shows weathering and iron-oxide staining; exact mineral proportions are uncertain from the image.
Formation & geological history
Intrusive igneous rock crystallized slowly from silica-rich magma deep in Earth’s crust, generally during Precambrian to Phanerozoic continental events. Surface weathering has altered and stained the exposed material.
Uses & applications
Used widely as dimension stone, countertops, monuments, paving, and aggregate; attractive polished pieces are collected but this rough fragment has modest value.
Geological facts
Granite’s visible interlocking crystals indicate slow cooling, unlike volcanic rhyolite. Pink coloration commonly reflects potassium feldspar, while dark flakes are likely biotite or hornblende.
Field identification & locations
Identify it by coarse visible grains, pale quartz, pink/white feldspar, and dark mica; it is harder than steel and does not usually react with dilute acid. Common worldwide in continental shields, plutons, and mountain belts.
