igneous
Quartz-bearing granite or pegmatitic rock
Granite, composed mainly of quartz, feldspar, and mica; exact identification is uncertain from the image
AI-generated identification · may be incorrectCoarse-grained, gray-brown rock with abundant pale quartz/feldspar and dark mica or amphibole. Typical hardness is about 6–7 Mohs, vitreous to dull luster, interlocking crystals, and no obvious cleavage as a whole rock; feldspar shows cleavage.
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Physical properties
Coarse-grained, gray-brown rock with abundant pale quartz/feldspar and dark mica or amphibole. Typical hardness is about 6–7 Mohs, vitreous to dull luster, interlocking crystals, and no obvious cleavage as a whole rock; feldspar shows cleavage.
Formation & geological history
Likely an intrusive igneous rock that crystallized slowly from silica-rich magma deep underground, generally during Precambrian to Phanerozoic geological time. The pale upper material may be a quartz-rich vein or weathered feldspathic portion.
Uses & applications
Granite is used for building stone, countertops, monuments, aggregate, and ornamental specimens; this irregular fragment has little commercial value.
Geological facts
Granite commonly contains visible quartz and feldspar crystals, while dark biotite or hornblende creates the speckled appearance. A glassy translucent grain that scratches glass is likely quartz.
Field identification & locations
Common worldwide, especially in continental mountain belts and exposed batholiths. Inspect the fresh surface, test hardness, and use dilute acid only if carbonate minerals are suspected; precise identification may require a thin section.
