igneous
Weathered granite or granitic gneiss
Granite; chiefly quartz, feldspar, and mica (possibly metamorphosed to gneiss)
AI-generated identification · may be incorrectCoarse, irregularly mottled gray-brown specimen with visible light feldspar/quartz and darker mica or mafic minerals; likely Mohs 6–7, vitreous to dull luster, massive texture, no obvious cleavage, and specific gravity about 2.6–2.8.
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Physical properties
Coarse, irregularly mottled gray-brown specimen with visible light feldspar/quartz and darker mica or mafic minerals; likely Mohs 6–7, vitreous to dull luster, massive texture, no obvious cleavage, and specific gravity about 2.6–2.8.
Formation & geological history
Granite crystallizes slowly from silica-rich magma deep in the crust, commonly during Precambrian to Phanerozoic continental mountain-building; weathering has rounded and stained this piece.
Uses & applications
Used extensively as dimension stone, countertops, monuments, aggregate, and landscaping rock; attractive polished pieces are collected but usually have modest value.
Geological facts
Granite’s interlocking crystals give it high durability, while iron-bearing minerals commonly produce the brown surface weathering visible here.
Field identification & locations
Identify it by its coarse interlocking grains, hardness, and lack of layering; distinguish gneiss by strong mineral banding. Common worldwide in continental shields and mountain belts.
