igneous
Weathered granite
Granite; quartz–feldspar–mica plutonic rock
AI-generated identification · may be incorrectLight gray, coarse crystalline, granular texture with scattered dark biotite/hornblende and iron-oxide staining. Hardness about 6–7 Mohs; nonmetallic luster, interlocking crystals, no prominent cleavage as a rock, and typically high density (~2.6–2.8 g/cm³).
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Physical properties
Light gray, coarse crystalline, granular texture with scattered dark biotite/hornblende and iron-oxide staining. Hardness about 6–7 Mohs; nonmetallic luster, interlocking crystals, no prominent cleavage as a rock, and typically high density (~2.6–2.8 g/cm³).
Formation & geological history
Forms when silica-rich magma cools slowly deep underground, producing visible quartz and feldspar crystals; commonly Paleozoic to Precambrian in exposed continental crust, though age cannot be determined from the image.
Uses & applications
Widely used as crushed aggregate, building stone, curbing, monuments, paving, and countertops; attractive polished pieces have decorative value.
Geological facts
The orange-brown patches are likely oxidation of iron-bearing minerals or surface coatings, not necessarily metallic ore.
Field identification & locations
Identify by its speckled quartz–feldspar–dark-mineral texture, hardness, and lack of layering or vesicles. Common in continental mountain belts and granite batholiths; an ordinary weathered fragment is usually worth $1–$10, while polished or unusually patterned specimens may bring $20–$100+.
