metamorphic
Weathered quartzite pebble (probable)
Quartzite; predominantly microcrystalline quartz (SiO₂), possibly iron-oxide stained
AI-generated identification · may be incorrectHardness about 7 Mohs; tan to ochre, dull-to-waxy surface, massive granular texture, and no obvious cleavage. The dark cavity may be a weathered fracture or inclusion; specific gravity is approximately 2.6–2.7.
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Physical properties
Hardness about 7 Mohs; tan to ochre, dull-to-waxy surface, massive granular texture, and no obvious cleavage. The dark cavity may be a weathered fracture or inclusion; specific gravity is approximately 2.6–2.7.
Formation & geological history
Quartzite forms when quartz-rich sandstone is recrystallized under metamorphic heat and pressure, commonly during mountain building; its exact geological age cannot be determined from the photograph. Rounding and surface weathering indicate transport in a stream, beach, or glacial deposit.
Uses & applications
Used as crushed stone, aggregate, road material, and decorative landscaping rock; attractive pieces may be collected or polished. This small, ordinary pebble has limited commercial value.
Geological facts
Quartzite is commonly mistaken for quartz-rich sandstone, but its grains are fused into a hard mosaic. Iron oxides can produce the yellow-brown coloration.
Field identification & locations
Test hardness against glass: genuine quartzite should scratch it; it typically does not fizz with dilute hydrochloric acid. Common in metamorphic mountain belts and downstream gravel beds.
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