igneous
Weathered granite
Granite; interlocking quartz–feldspar–mica aggregate
AI-generated identification · may be incorrectCoarse-grained, speckled cream, gray, and tan rock with quartz and feldspar, likely biotite/hornblende; vitreous quartz luster, Mohs hardness about 6–7, no strong cleavage as a whole, specific gravity about 2.63–2.75.
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Physical properties
Coarse-grained, speckled cream, gray, and tan rock with quartz and feldspar, likely biotite/hornblende; vitreous quartz luster, Mohs hardness about 6–7, no strong cleavage as a whole, specific gravity about 2.63–2.75.
Formation & geological history
An intrusive igneous rock crystallized slowly from silica-rich magma deep in the crust, commonly during Precambrian to Phanerozoic continental mountain-building; surface weathering rounded this cobble.
Uses & applications
Used widely as building stone, countertops, paving, monuments, aggregate, and landscaping rock; this weathered specimen has modest decorative or educational value.
Geological facts
The large crystals indicate slow underground cooling. Orange-brown patches are likely iron-stained feldspar or weathering products rather than a separate mineral.
Field identification & locations
Identify it by visible interlocking light and dark grains, abundant pale feldspar, translucent gray quartz, and occasional black mica; common in continental regions worldwide and glacial stream deposits.
