metamorphic
Weathered quartzite or quartz-rich sandstone
Quartzite, composed predominantly of quartz (SiO₂); field identification is uncertain from the photograph
AI-generated identification · may be incorrectTan to rusty-brown, strongly weathered, granular and hard-looking with a pale quartz-rich margin and darker iron-oxide-stained center; quartz has Mohs hardness 7, vitreous to dull luster, and no cleavage.
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Physical properties
Tan to rusty-brown, strongly weathered, granular and hard-looking with a pale quartz-rich margin and darker iron-oxide-stained center; quartz has Mohs hardness 7, vitreous to dull luster, and no cleavage.
Formation & geological history
Likely formed when quartz sandstone was compacted and recrystallized during metamorphism, then exposed and chemically weathered; age depends on its source formation and cannot be determined visually.
Uses & applications
Commonly used as crushed aggregate, paving stone, building stone, and occasionally ornamental material; this isolated specimen has little commercial value.
Geological facts
Iron oxides produce the rusty coloration, while the darker patch may reflect staining, inclusions, or surface soil rather than a distinct mineral.
Field identification & locations
Look for grains fused so tightly that the rock fractures through quartz rather than around grains, unlike ordinary sandstone; common worldwide in metamorphic belts and glacial deposits.
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