igneous
Weathered granite or granitic gneiss
Quartz–feldspar–mica aggregate; likely biotite granite, possibly weakly gneissic
AI-generated identification · may be incorrectCoarse-grained, mottled white/gray, pink-brown, and black material with visible quartz, feldspar, and dark mica/amphibole. Interlocking crystalline texture; typical hardness about 6–7 Mohs, vitreous quartz and dull feldspar luster, no obvious cleavage at specimen scale.…
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Physical properties
Coarse-grained, mottled white/gray, pink-brown, and black material with visible quartz, feldspar, and dark mica/amphibole. Interlocking crystalline texture; typical hardness about 6–7 Mohs, vitreous quartz and dull feldspar luster, no obvious cleavage at specimen scale. The rusty brown areas are likely iron-oxide weathering.
Formation & geological history
Formed by slow cooling of silica-rich magma deep underground, generally Precambrian to Paleozoic in age depending on source; surface oxidation and weathering produced the brown staining. Granitic rocks and glacially transported cobbles are common around southern Quebec near 45.5°N, 73.6°W.
Uses & applications
Used widely as crushed stone, aggregate, building stone, and countertops; attractive pieces may be polished, though this specimen appears ordinary and weathered.
Geological facts
Granite is defined by abundant quartz and alkali feldspar; gneissic specimens show compositional banding or foliation, which is not strongly evident here.
Field identification & locations
Identify by testing for abundant glassy quartz, pale feldspar, and scattered black mica; it should not fizz with dilute acid and should scratch glass. Exact identification would require a fresh surface or thin section, since the image could also show a granitic gneiss or pegmatitic fragment.
