metamorphic
Red-orange quartzite or iron-stained quartz
Quartzite; predominantly microcrystalline quartz (SiO₂), with iron-oxide staining
AI-generated identification · may be incorrectHardness about 7 Mohs; reddish-orange, granular and massive, with a dull to slightly vitreous luster. Quartzite has no cleavage, irregular fracture, and typically high durability; the image’s low lighting makes exact identification uncertain.
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Physical properties
Hardness about 7 Mohs; reddish-orange, granular and massive, with a dull to slightly vitreous luster. Quartzite has no cleavage, irregular fracture, and typically high durability; the image’s low lighting makes exact identification uncertain.
Formation & geological history
Quartzite forms when quartz-rich sandstone is recrystallized under heat and pressure during metamorphism; iron oxides produce the red-orange coloration. Formation ages vary widely, commonly from Precambrian to Paleozoic rocks.
Uses & applications
Used as crushed stone, aggregate, paving, wall stone, and occasionally decorative material; attractive pieces may be collected but are rarely used as gemstones.
Geological facts
A true quartzite resists scratching by a steel knife and usually breaks through quartz grains rather than around them. Similar-looking reddish specimens can be jasper, quartz-rich sandstone, or iron-stained quartz.
Field identification & locations
Common in metamorphic mountain belts worldwide, including the Appalachians, Rocky Mountains, India, Brazil, and Scandinavia. Test hardness, inspect for visible sand grains, and compare streak: quartzite generally leaves a white or colorless streak.
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