igneous
Weathered granitic rock (likely granite or granodiorite)
Granite–granodiorite, composed mainly of quartz, feldspar, and biotite/hornblende
AI-generated identification · may be incorrectTypically medium- to coarse-grained, gray to pinkish, with a granular texture and dull to glassy quartz luster; Mohs hardness about 6–7, no cleavage as a rock, and specific gravity around 2.6–2.8. The specimen appears strongly weathered, so individual crystals are indistinct.
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Physical properties
Typically medium- to coarse-grained, gray to pinkish, with a granular texture and dull to glassy quartz luster; Mohs hardness about 6–7, no cleavage as a rock, and specific gravity around 2.6–2.8. The specimen appears strongly weathered, so individual crystals are indistinct.
Formation & geological history
A plutonic igneous rock that crystallized slowly from magma deep underground, commonly during Precambrian to Mesozoic mountain-building events; later uplift and surface weathering exposed it.
Uses & applications
Used as crushed stone, road aggregate, building stone, monuments, and countertops; this weathered field piece has little jewelry or commercial value.
Geological facts
Granite commonly develops rounded weathering forms and decomposes to sandy, feldspar-rich soil. Its exact identification would require a fresh surface or thin section.
Field identification & locations
Common in continental crust and mountain belts worldwide, including the Sierra Nevada, Appalachians, Canadian Shield, and many volcanic-arc regions. Look for visible quartz and feldspar grains, interlocking texture, and inability to scratch with a steel knife; field value is usually $1–$10, or roughly $5–$30 if attractive and collectable.
