igneous
Weathered granite
Granite; chiefly quartz, potassium feldspar, plagioclase, and biotite/hornblende
AI-generated identification · may be incorrectMedium- to coarse-grained, speckled gray, pink, and black rock with a granular texture and dull to slightly vitreous luster. Mohs hardness is about 6–7; cleavage is absent as a rock, though feldspar grains cleave, and specific gravity is approximately 2.63–2.75.
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Physical properties
Medium- to coarse-grained, speckled gray, pink, and black rock with a granular texture and dull to slightly vitreous luster. Mohs hardness is about 6–7; cleavage is absent as a rock, though feldspar grains cleave, and specific gravity is approximately 2.63–2.75.
Formation & geological history
An intrusive igneous rock formed by slow cooling of silica-rich magma deep in the crust, commonly during Precambrian to Phanerozoic mountain-building events. Surface weathering has rounded and oxidized its exposed edges.
Uses & applications
Widely used as building stone, countertops, monuments, paving, aggregate, and landscaping material; attractive polished pieces have modest decorative value.
Geological facts
The visible interlocking grains indicate crystallization underground rather than volcanic cooling. Pink tones generally reflect potassium feldspar, gray translucent grains quartz, and dark flecks biotite or hornblende.
Field identification & locations
Identify it by its visible interlocking quartz and feldspar grains, lack of layering, and inability to scratch quartz with a steel knife. Common worldwide, especially in continental shields and mountain batholiths.
