igneous
Weathered granite or granitic gneiss
Granite; chiefly quartz, feldspar, and mica
AI-generated identification · may be incorrectCoarse-grained, gray-brown, granular texture with visible dark mica and light feldspar/quartz; vitreous to dull luster, no obvious cleavage as a whole, Mohs hardness about 6–7, specific gravity 2.6–2.8. Strong weathering and staining obscure the original fabric.
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Physical properties
Coarse-grained, gray-brown, granular texture with visible dark mica and light feldspar/quartz; vitreous to dull luster, no obvious cleavage as a whole, Mohs hardness about 6–7, specific gravity 2.6–2.8. Strong weathering and staining obscure the original fabric.
Formation & geological history
Likely an ancient continental-crust intrusive rock, crystallized slowly from silica-rich magma roughly hundreds of millions to billions of years ago, then exposed and rounded by uplift and weathering. The foliation-like appearance could indicate granitic gneiss, but the image is insufficient for certainty.
Uses & applications
Commonly used as crushed aggregate, road stone, building stone, monuments, and countertops; this weathered individual has little commercial value.
Geological facts
Granite’s interlocking quartz and feldspar crystals make it durable, while iron-bearing minerals commonly produce the brown oxidation stains visible here.
Field identification & locations
Identify it by its speckled interlocking grains, abundant pale feldspar, translucent quartz, and scattered black mica; a glassy scratch test and lack of acid reaction support granite. Common worldwide in continental shields and mountain belts.
