igneous
Granite or granitic gneiss pebble
Coarse-grained quartz–feldspar–mica rock; likely granite, possibly foliated gneiss
AI-generated identification · may be incorrectHardness about 6–7 Mohs; mottled pink-orange, white, gray, and black; granular texture with vitreous quartz and feldspar luster. Interlocking crystals are visible, with no obvious cleavage at the specimen scale; specific gravity about 2.6–2.8.
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Physical properties
Hardness about 6–7 Mohs; mottled pink-orange, white, gray, and black; granular texture with vitreous quartz and feldspar luster. Interlocking crystals are visible, with no obvious cleavage at the specimen scale; specific gravity about 2.6–2.8.
Formation & geological history
Likely crystallized slowly from silica-rich magma deep in the crust, producing visible crystals; comparable granites commonly formed during Precambrian to Phanerozoic mountain-building events. Rounded edges indicate transport by a river, beach, or glacial action.
Uses & applications
Used as crushed aggregate, building stone, paving, monuments, countertops, and decorative gravel; this small rounded specimen has modest collecting value.
Geological facts
The pink/orange grains are commonly potassium feldspar, pale grains are quartz or plagioclase, and black grains are biotite or hornblende. A magnet may produce a weak response if magnetite is present.
Field identification & locations
Identify it by its coarse interlocking grains and speckled appearance; granite is widespread worldwide, while gneiss typically shows banding or aligned minerals. A fresh surface and hand lens help distinguish granite from similar volcanic or metamorphic rocks.
