igneous
Quartz-rich pegmatite or quartz vein fragment
Massive to coarse-grained quartz (SiO₂), likely with feldspar and minor mica
AI-generated identification · may be incorrectWhite to gray, vitreous to pearly luster, uneven fracture, and interlocking coarse crystals; quartz hardness is 7 Mohs, while associated feldspar is about 6. No distinct cleavage is visible. Specific gravity is approximately 2.6–2.7.
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Physical properties
White to gray, vitreous to pearly luster, uneven fracture, and interlocking coarse crystals; quartz hardness is 7 Mohs, while associated feldspar is about 6. No distinct cleavage is visible. Specific gravity is approximately 2.6–2.7.
Formation & geological history
Most likely crystallized slowly from silica-rich magma in a pegmatite or formed as a hydrothermal quartz vein, generally in ancient continental crust. The exact age cannot be determined from the photograph.
Uses & applications
Used as aggregate, silica feedstock, and ornamental stone; attractive quartz specimens may be collected, but this piece appears common and has little jewelry value.
Geological facts
The sugary, interlocking texture suggests quartz with feldspar rather than a single crystal. Weathering has rounded the fragment and accentuated fractures and cavities.
Field identification & locations
Look for glassy quartz grains, blocky feldspar cleavage, and hardness sufficient to scratch ordinary glass; acid testing is unnecessary. Quartz-rich rocks occur worldwide, especially in granite and metamorphic terranes.
