metamorphic
Iron-stained quartzite or quartz-rich rock
Quartzite; predominantly microcrystalline quartz (SiO₂) with iron-oxide staining
AI-generated identification · may be incorrectHardness about 7 Mohs; brown, orange, gray, and purplish coloration; mostly vitreous to dull luster and granular texture. Quartzite has no prominent cleavage, irregular fracture, and typically high durability; the visible rusty tones likely come from hematite or limonite.
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Physical properties
Hardness about 7 Mohs; brown, orange, gray, and purplish coloration; mostly vitreous to dull luster and granular texture. Quartzite has no prominent cleavage, irregular fracture, and typically high durability; the visible rusty tones likely come from hematite or limonite.
Formation & geological history
Forms when quartz-rich sandstone is metamorphosed under elevated heat and pressure, recrystallizing the sand grains into interlocking quartz. Its precise geological age and source cannot be determined from the photograph.
Uses & applications
Used as crushed stone, aggregate, paving, building stone, and occasionally as a decorative or lapidary material. This rough piece has little jewelry value unless it polishes attractively.
Geological facts
The specimen appears weathered and iron-rich rather than a single transparent crystal or gemstone. A steel file should generally fail to scratch fresh quartzite, while quartz can scratch ordinary glass.
Field identification & locations
Common in metamorphic mountain belts and exposed quartzite ridges worldwide, including the Appalachians, western United States, Brazil, India, and Scandinavia. Confirm by testing hardness and examining a freshly broken surface for fused quartz grains.
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