metamorphic
Weathered quartz-rich rock, possibly quartzite
Quartzite (mostly SiO₂), with iron-oxide staining; exact identification is uncertain from the photograph
AI-generated identification · may be incorrectHardness about 7 Mohs; gray-white, granular and massive, with rusty orange-brown hematite/goethite staining. Typically vitreous to dull luster, interlocking quartz grains, and no obvious cleavage.
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Physical properties
Hardness about 7 Mohs; gray-white, granular and massive, with rusty orange-brown hematite/goethite staining. Typically vitreous to dull luster, interlocking quartz grains, and no obvious cleavage.
Formation & geological history
Quartzite forms when quartz-rich sandstone is recrystallized under heat and pressure during metamorphism; iron-bearing groundwater commonly creates the surface staining. Its age depends on the source formation and cannot be determined visually.
Uses & applications
Common quartzite is used as aggregate, road stone, building stone, and landscaping material; attractive pieces may be collected or polished but have little gem value.
Geological facts
The rusty color is usually iron oxides rather than the primary rock color. Quartzite is generally harder and more resistant to weathering than its sandstone precursor.
Field identification & locations
Look for a gritty-to-sparkly quartz texture, conchoidal fracture, lack of clay softness, and inability to scratch it with a steel knife; a glass scratch test can help, though it may damage the specimen. Quartzite occurs widely in metamorphic mountain belts worldwide.
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