igneous
Likely granite
Granite; mainly quartz, feldspar, and mica (typically biotite)
AI-generated identification · may be incorrectCoarse-grained, speckled black-and-white rock with a granular texture; individual crystals are visible but blurred in the image. Hardness is roughly 6–7 Mohs, with a vitreous-to-dull luster, no consistent cleavage as a whole, and specific gravity around 2.6–2.7.
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Physical properties
Coarse-grained, speckled black-and-white rock with a granular texture; individual crystals are visible but blurred in the image. Hardness is roughly 6–7 Mohs, with a vitreous-to-dull luster, no consistent cleavage as a whole, and specific gravity around 2.6–2.7.
Formation & geological history
Granite forms when silica-rich magma cools slowly deep within continental crust, allowing large crystals to grow; individual specimens may range from Precambrian to recent geologic ages.
Uses & applications
Widely used as dimension stone, countertops, monuments, paving, aggregate, and decorative stone; small pieces have modest collecting value.
Geological facts
The dark grains are likely biotite or hornblende, while the light grains are feldspar and quartz. The specimen’s triangular shape appears to result from natural breakage or cutting.
Field identification & locations
Identify it by its interlocking visible crystals, quartz-like gray grains, white or pink feldspar, and dark mica; it commonly occurs in continental mountain belts worldwide. A hand lens and scratch test help distinguish it from fine-grained basalt.
