metamorphic
Weathered quartz-bearing sandstone or quartzite
Quartzite (SiO₂-rich), possibly weakly metamorphosed sandstone
AI-generated identification · may be incorrectTan-brown, blocky specimen with abundant pale quartz grains/veins and iron-oxide staining; likely Mohs 6.5–7, vitreous to dull luster, massive texture, and no obvious cleavage. A fresh fracture should be granular and quartz-rich; quartzite breaks through grains rather than around them.
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Physical properties
Tan-brown, blocky specimen with abundant pale quartz grains/veins and iron-oxide staining; likely Mohs 6.5–7, vitreous to dull luster, massive texture, and no obvious cleavage. A fresh fracture should be granular and quartz-rich; quartzite breaks through grains rather than around them.
Formation & geological history
Likely formed when quartz-rich sandstone was compacted and weakly metamorphosed, recrystallizing quartz grains; the exact geological age cannot be determined from the photograph. Weathering produced the brown iron staining and rough surface.
Uses & applications
Quartzite is used as crushed stone, road aggregate, landscaping rock, and occasionally building or dimension stone; attractive varieties are collected but this specimen appears low-grade.
Geological facts
Its identification is uncertain from the image because grain boundaries and texture are weathered; it may instead be ferruginous sandstone. Quartz-rich rocks commonly resist weathering and form ridges or resistant outcrops.
Field identification & locations
Check whether a steel nail scratches it (quartzite generally does not), and whether a fresh surface shows fused interlocking quartz grains; dilute acid should not fizz. Common in metamorphic belts and sandstone-derived terrains worldwide.
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