igneous
Coarse-grained granite or granitic gneiss
Quartz–feldspar–mica granite; possibly foliated granitic gneiss
AI-generated identification · may be incorrectHardness about 6–7 Mohs; pink-white and gray, with black mica/amphibole, glassy quartz, and blocky feldspar. Crystalline, granular texture; feldspar cleavage is visible, but the specimen lacks obvious strong foliation.
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Physical properties
Hardness about 6–7 Mohs; pink-white and gray, with black mica/amphibole, glassy quartz, and blocky feldspar. Crystalline, granular texture; feldspar cleavage is visible, but the specimen lacks obvious strong foliation.
Formation & geological history
Formed by slow cooling of silica-rich magma deep in the continental crust, likely during Precambrian to younger continental-crust events; if distinctly banded, it may represent metamorphosed granite (gneiss).
Uses & applications
Common granite is used for dimension stone, countertops, monuments, aggregate, and construction. This hand specimen has modest collector value unless it displays exceptional texture or locality significance.
Geological facts
The pale pink grains are likely potassium feldspar, gray translucent grains are quartz, and dark grains are biotite or hornblende. Its coarse crystals indicate slow underground cooling rather than volcanic eruption.
Field identification & locations
Look for interlocking quartz, feldspar, and dark mica; granite is massive, whereas gneiss shows compositional banding. Common worldwide, especially in continental shields and mountain belts; a glassy streak-free surface and hardness distinguish it from softer sedimentary rocks.
