igneous
Quartz-rich granite or granitic pegmatite
Granite; predominantly quartz (SiO₂), feldspar, and possibly mica
AI-generated identification · may be incorrectCoarse-grained, gray-white specimen with abundant reflective crystal faces and no obvious layering; likely Mohs 6–7, vitreous quartz luster, with feldspar cleavage and granular interlocking crystals. Exact identification is limited by the close, slightly blurred photograph.
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Physical properties
Coarse-grained, gray-white specimen with abundant reflective crystal faces and no obvious layering; likely Mohs 6–7, vitreous quartz luster, with feldspar cleavage and granular interlocking crystals. Exact identification is limited by the close, slightly blurred photograph.
Formation & geological history
Slow crystallization of silica-rich magma deep in the crust, commonly during Precambrian to Phanerozoic continental mountain-building; pegmatitic varieties form from late, water-rich melt. Common worldwide, including India, Brazil, Madagascar, the United States, and Europe.
Uses & applications
Granite is used for building stone, countertops, monuments, aggregate, and specimens; attractive quartz-rich pieces may be collected, while gem value is generally low unless crystals are unusually large or clear.
Geological facts
The bright sparkles likely come from quartz or mica cleavage surfaces, but metallic-looking reflections can also result from a polished or coated surface.
Field identification & locations
Identify in the field by its interlocking coarse grains, hardness, and lack of fossils or sedimentary layering; quartz scratches glass, whereas mica flakes and feldspar cleavage help distinguish it. Typical hand specimens are worth about $2–$20; unusually aesthetic pegmatites may reach $30–$100.
