igneous
Light-colored granite or granitic gneiss cobble
Granite, chiefly quartz, feldspar, and minor mica; exact identification is uncertain from the photograph
AI-generated identification · may be incorrectCoarse crystalline, pale gray-white, with a dull to slightly sparkly luster and irregular fracture; typical hardness is about 6–7 Mohs and specific gravity 2.6–2.8. The image suggests weathered, rounded aggregate rather than a fresh display specimen.
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Physical properties
Coarse crystalline, pale gray-white, with a dull to slightly sparkly luster and irregular fracture; typical hardness is about 6–7 Mohs and specific gravity 2.6–2.8. The image suggests weathered, rounded aggregate rather than a fresh display specimen.
Formation & geological history
Granite crystallizes slowly from silica-rich magma deep in continental crust, commonly during Precambrian to Phanerozoic mountain-building events; gneissic varieties form by metamorphism. Rounded surfaces result from transport and abrasion.
Uses & applications
Used extensively as crushed stone, road aggregate, concrete aggregate, paving, countertops, monuments, and landscaping gravel; attractive pieces may be used decoratively.
Geological facts
Visible quartz and feldspar grains, if present, distinguish granite from fine-grained limestone or quartzite. The background appears to be a bed of similar crushed aggregate.
Field identification & locations
Identify by visible interlocking grains, pale feldspar, glassy quartz, and occasional black mica; it should not fizz with dilute hydrochloric acid unless carbonate material is present. Common worldwide, especially in continental shield and mountain regions.
