igneous
Granite
Coarse-grained felsic intrusive igneous rock, typically quartz + alkali feldspar + plagioclase with biotite/hornblende
AI-generated identification · may be incorrectHardness about 6–7; gray, white, and black speckled appearance; generally vitreous quartz luster and crystalline granular texture, with no obvious cleavage as a whole rock. Specific gravity is typically 2.63–2.75.
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Physical properties
Hardness about 6–7; gray, white, and black speckled appearance; generally vitreous quartz luster and crystalline granular texture, with no obvious cleavage as a whole rock. Specific gravity is typically 2.63–2.75.
Formation & geological history
Forms when silica-rich magma cools slowly deep within continental crust, allowing visible crystals to grow; specimens may range from Precambrian to much younger, depending on source body.
Uses & applications
Widely used as building stone, countertops, paving, monuments, aggregate, and landscaping rock; ordinary hand specimens have little commercial value.
Geological facts
The visible interlocking grains and contrasting light feldspar/quartz with dark mica or amphibole are characteristic of granite. Exact identification would benefit from a fresh surface or mineral tests.
Field identification & locations
Common worldwide in continental mountain belts and exposed plutons; identify by coarse interlocking grains, abundant light minerals, and scattered black mica/amphibole. Approximate value: $1–$10 for a common loose specimen, higher if unusually attractive or labeled by locality.
