igneous
Quartz-rich feldspathic rock, possibly granite or pegmatite fragment
Granite/pegmatite; chiefly quartz (SiO₂), feldspar, and minor dark mica or amphibole
AI-generated identification · may be incorrectCoarse, irregular granular texture with translucent gray-white quartz, pale feldspar, and dark grains; vitreous quartz luster, no obvious cleavage in quartz, Mohs hardness about 6–7, typically specific gravity 2.6–2.7. The small, weathered specimen is insufficient for a definitive identification.
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Physical properties
Coarse, irregular granular texture with translucent gray-white quartz, pale feldspar, and dark grains; vitreous quartz luster, no obvious cleavage in quartz, Mohs hardness about 6–7, typically specific gravity 2.6–2.7. The small, weathered specimen is insufficient for a definitive identification.
Formation & geological history
Likely crystallized slowly from silica-rich magma deep underground, probably during Precambrian or younger continental crust formation; pegmatitic varieties form from late-stage, volatile-rich magma and may contain especially large crystals.
Uses & applications
Granite is used for dimension stone, countertops, aggregate, and monuments; pegmatites are collected for quartz, feldspar, mica, and gem minerals. This fragment has mainly modest educational or specimen value.
Geological facts
Visible sparkle may come from mica, while the translucent grains are likely quartz. A streak test, hardness test, and closer examination of crystal boundaries would distinguish granite from pegmatite or weathered metamorphic rock.
Field identification & locations
Common in continental terrains worldwide, including the United States, Canada, Brazil, India, and Scandinavia. Look for interlocking visible crystals; avoid acid testing unless carbonate minerals are suspected.
