metamorphic
Weathered quartz-rich rock, likely milky quartz/quartzite
Quartz (SiO₂), possibly quartzite with minor iron-oxide staining
AI-generated identification · may be incorrectHardness about 7 Mohs; white to cream with tan-brown staining, translucent patches, and vitreous to waxy luster. Quartz has a trigonal crystal structure and no cleavage, producing irregular fractures; quartzite is typically very tough and massive.
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Physical properties
Hardness about 7 Mohs; white to cream with tan-brown staining, translucent patches, and vitreous to waxy luster. Quartz has a trigonal crystal structure and no cleavage, producing irregular fractures; quartzite is typically very tough and massive.
Formation & geological history
Likely formed from quartz-rich sandstone metamorphosed by heat and pressure, with later weathering and iron-oxide staining. The exact geological age cannot be determined from the photograph.
Uses & applications
Common quartzite is used as crushed aggregate, road stone, building stone, and landscaping rock; attractive pieces may be collected or polished but have limited gem value.
Geological facts
The rounded surface suggests prolonged weathering or transport. A steel file should not scratch fresh quartz, while quartzite commonly gives a glassy scratch and may contain interlocking quartz grains.
Field identification & locations
Common in metamorphic belts and stream gravels worldwide, especially mountain regions. Confirm by testing hardness, examining a fresh surface for fused quartz grains, and checking for acid reaction—none is expected.
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