igneous
Weathered granite or granitic gneiss pebble
Granite; chiefly quartz, alkali feldspar, plagioclase, and minor biotite/hornblende
AI-generated identification · may be incorrectHardness about 6–7 Mohs; tan to gray, granular texture, dull to weakly vitreous luster, and no obvious cleavage. The rounded shape and iron-oxide staining indicate natural weathering and abrasion.
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Physical properties
Hardness about 6–7 Mohs; tan to gray, granular texture, dull to weakly vitreous luster, and no obvious cleavage. The rounded shape and iron-oxide staining indicate natural weathering and abrasion.
Formation & geological history
Formed by slow crystallization of silica-rich magma deep in the continental crust, commonly hundreds of millions to billions of years ago; later exposed and rounded by erosion, transport, or glacial action.
Uses & applications
Used as aggregate, building stone, paving, monuments, and landscaping rock; this small specimen has mainly educational or modest collecting value.
Geological facts
Visible speckling reflects interlocking mineral grains rather than layered sediment. The image does not clearly resolve foliation, so precise identification as granite versus granitic gneiss is limited.
Field identification & locations
Look for interlocking quartz and feldspar grains, occasional dark mica, high scratch resistance, and lack of fizz with dilute hydrochloric acid. Common in continental mountain belts, glacial deposits, river gravels, and coastal cobbles.
