igneous
Granite
Coarse-grained felsic plutonic rock, chiefly quartz, alkali feldspar, plagioclase, and biotite/hornblende
AI-generated identification · may be incorrectTypically Mohs 6–7; mottled cream, gray, black, and brown with a granular texture and vitreous-to-dull luster. Interlocking crystals show no foliation; cleavage belongs to individual feldspar crystals rather than the rock.
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Physical properties
Typically Mohs 6–7; mottled cream, gray, black, and brown with a granular texture and vitreous-to-dull luster. Interlocking crystals show no foliation; cleavage belongs to individual feldspar crystals rather than the rock.
Formation & geological history
Granite crystallizes slowly from silica-rich magma deep in continental crust, commonly during Precambrian to Cenozoic mountain-building events. The specimen appears naturally weathered and rounded.
Uses & applications
Widely used for building stone, countertops, monuments, paving, aggregate, and decorative objects; ordinary hand specimens have modest collector value.
Geological facts
Its speckled appearance results from contrasting light feldspar/quartz and dark mica or amphibole. Weathering commonly rounds edges and produces rusty staining from oxidation of iron-bearing minerals.
Field identification & locations
Identify it by visible interlocking grains, abundant pale feldspar, translucent-gray quartz, and scattered black mica/amphibole; it will not fizz with dilute hydrochloric acid. Common worldwide, especially in continental shields and mountain belts.
