metamorphic
Iron-stained quartzite (likely)
Quartzite, predominantly quartz (SiO₂), with iron-oxide staining and possible mica/feldspar
AI-generated identification · may be incorrectHardness about 7 Mohs; brown, reddish-purple, and gray coloration; vitreous to earthy luster; granular interlocking quartz texture with no obvious cleavage. The rough, weathered surface and translucent edges are consistent with quartz-rich rock.
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Physical properties
Hardness about 7 Mohs; brown, reddish-purple, and gray coloration; vitreous to earthy luster; granular interlocking quartz texture with no obvious cleavage. The rough, weathered surface and translucent edges are consistent with quartz-rich rock.
Formation & geological history
Formed when quartz-rich sandstone was deeply buried and metamorphosed, recrystallizing into quartzite; iron-bearing fluids later produced the brown-red staining. Age depends on its source region and cannot be determined from the photograph.
Uses & applications
Commonly used as crushed stone, aggregate, paving, and building/decorative stone; attractive pieces may be collected, but this specimen has no obvious gemstone-grade value.
Geological facts
Quartzite commonly breaks across grains rather than around them and is typically harder and more resistant to weathering than sandstone. Purple tones may reflect hematite or other iron oxides.
Field identification & locations
Look for a gritty-to-sugary quartz texture, strong resistance to scratching by steel, and little or no visible layering or cleavage; it may occur in metamorphic mountain belts and quartz-rich gravel deposits.
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