igneous
Weathered granitic rock (granite or granodiorite)
Coarse crystalline quartz–feldspar–mica aggregate; commonly granite, approximately quartz + K-feldspar/plagioclase + biotite/muscovite
AI-generated identification · may be incorrectHardness about 6–7 Mohs; mottled cream, gray, tan, and brown with visible interlocking grains, vitreous quartz, pearly feldspar, and locally shiny mica. Massive, nonfoliated texture; no obvious cleavage at the rock scale; specific gravity roughly 2.6–2.8.
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Physical properties
Hardness about 6–7 Mohs; mottled cream, gray, tan, and brown with visible interlocking grains, vitreous quartz, pearly feldspar, and locally shiny mica. Massive, nonfoliated texture; no obvious cleavage at the rock scale; specific gravity roughly 2.6–2.8.
Formation & geological history
Slow cooling of silica-rich magma deep in continental crust produced the coarse crystals, typically during Precambrian to Phanerozoic plutonic events; surface weathering has rounded and stained the specimen.
Uses & applications
Used extensively as dimension stone, countertops, monuments, aggregate, and landscaping rock; attractive pieces may be polished for decorative use, though this specimen appears ordinary.
Geological facts
The pale reflective grains are likely feldspar and quartz, while darker sparkles may be mica; iron-oxide weathering can create the tan-brown surface.
Field identification & locations
Identify by coarse interlocking grains, hardness, lack of layering, and inability to scratch quartz; granite is widespread in continental mountain belts and exposed plutons worldwide. Exact granite versus granodiorite requires mineral proportions or thin-section analysis.
