metamorphic
Weathered quartz-rich metamorphic rock, likely quartzite
Quartzite (mostly SiO₂), possibly iron-stained metaconglomerate or quartz-rich gneiss
AI-generated identification · may be incorrectHardness about 7 Mohs; massive, granular texture with white, gray, tan, and reddish-brown iron-oxide staining. Vitreous to dull luster, interlocking quartz crystals, and little or no cleavage; the rounded shape suggests natural abrasion or transport.
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Physical properties
Hardness about 7 Mohs; massive, granular texture with white, gray, tan, and reddish-brown iron-oxide staining. Vitreous to dull luster, interlocking quartz crystals, and little or no cleavage; the rounded shape suggests natural abrasion or transport.
Formation & geological history
Formed when quartz-rich sandstone was recrystallized under heat and pressure, commonly during Precambrian to Paleozoic mountain-building; surface oxidation produced the rusty colors. The exact age and subtype cannot be confirmed from a photograph.
Uses & applications
Used as durable aggregate, road stone, riprap, building stone, and occasionally ornamental material; attractive pieces are collected but usually have modest commercial value.
Geological facts
Quartzite commonly breaks across quartz grains rather than around them, unlike weak sandstone. Dark bands may indicate mica, iron oxides, or remnants of original bedding.
Field identification & locations
Likely locations include mountain belts, glacial deposits, stream gravels, and resistant ridges worldwide. A steel nail should not scratch it; diluted hydrochloric acid should not fizz unless carbonate cement is present.
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