igneous
Weathered granite or granitic gneiss
Granite–gneiss, chiefly quartz, feldspar, and biotite/amphibole
AI-generated identification · may be incorrectCoarse, granular and weakly banded, with pale beige feldspar/quartz and greenish weathering; likely Mohs 6–7, vitreous-to-dull luster, poor cleavage overall, and specific gravity about 2.6–2.8. The rounded shape and rough surface indicate natural weathering or abrasion.
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Physical properties
Coarse, granular and weakly banded, with pale beige feldspar/quartz and greenish weathering; likely Mohs 6–7, vitreous-to-dull luster, poor cleavage overall, and specific gravity about 2.6–2.8. The rounded shape and rough surface indicate natural weathering or abrasion.
Formation & geological history
Granite crystallizes slowly from silica-rich magma deep underground, generally in Precambrian to Phanerozoic continental crust; gneiss forms when such rock is metamorphosed under high temperature and pressure. The exact subtype and age cannot be confirmed from the photograph alone.
Uses & applications
Used as crushed stone, aggregate, building stone, monuments, and occasionally decorative landscaping material; this specimen has limited gem or commercial value.
Geological facts
The pale grains are probably quartz and feldspar, while the green areas may be chlorite, epidote, or weathered mafic minerals. Distinguish it from sandstone by its interlocking crystalline texture rather than visibly cemented grains.
Field identification & locations
Common in continental mountain belts and glacial deposits worldwide. A hand lens should reveal interlocking crystals; a streak test is white, and quartz-rich portions resist a steel knife, while dilute acid should show little or no reaction.
