igneous
Granite (likely weathered biotite granite)
Felsic intrusive igneous rock; mainly quartz, potassium feldspar, plagioclase, and biotite mica
AI-generated identification · may be incorrectCoarse-grained, speckled gray-white rock with visible interlocking crystals and mica sparkle; Mohs hardness about 6–7, vitreous to dull luster, poor cleavage as a rock, density roughly 2.6–2.7 g/cm³.
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Physical properties
Coarse-grained, speckled gray-white rock with visible interlocking crystals and mica sparkle; Mohs hardness about 6–7, vitreous to dull luster, poor cleavage as a rock, density roughly 2.6–2.7 g/cm³.
Formation & geological history
Formed when silica-rich magma cooled slowly deep underground, allowing large crystals to grow; commonly Paleozoic to Precambrian, though age depends on locality.
Uses & applications
Widely used as crushed stone, aggregate, paving, monuments, countertops, and building stone; this small weathered fragment has little commercial value.
Geological facts
The dark flakes are probably biotite mica, while translucent grains are quartz and pale grains are feldspar. Surface weathering can make granite appear rusty or unusually dull.
Field identification & locations
Identify it by its coarse salt-and-pepper texture, interlocking crystals, and lack of layering or foliation; common in continental mountain belts and glacial deposits. Exact identification would require a fresh surface or thin section.
