igneous
Weathered quartz-rich rock, possibly granite or pegmatite fragment
Uncertain; likely quartz–feldspar aggregate, potentially granitic pegmatite
AI-generated identification · may be incorrectSmall, tan-gray, coarse-grained fragment with a dull to slightly vitreous luster and irregular fracture; visible grains suggest quartz and altered feldspar. Estimated hardness 6–7 Mohs; cleavage is not clearly visible and specific gravity is approximately 2.6–2.7.
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Physical properties
Small, tan-gray, coarse-grained fragment with a dull to slightly vitreous luster and irregular fracture; visible grains suggest quartz and altered feldspar. Estimated hardness 6–7 Mohs; cleavage is not clearly visible and specific gravity is approximately 2.6–2.7.
Formation & geological history
Likely crystallized slowly from silica-rich magma in the continental crust, then weathered and broken near the surface. Its precise geological age and identity cannot be determined from this photograph alone.
Uses & applications
Common granite-like material is used for construction aggregate, monuments, and countertops; unexceptional fragments generally have no commercial or collector value.
Geological facts
Quartz-rich igneous rocks commonly develop interlocking crystals, while weathering can produce the tan coating seen here.
Field identification & locations
Look for distinct quartz grains that resist scratching glass and feldspar grains showing cleavage; a fresh broken surface and streak, hardness, and acid tests would improve identification. Common worldwide in continental plutonic terrains.
