metamorphic
Iron-rich quartzite or weathered ironstone
Quartzite, chiefly SiO₂, with iron-oxide minerals such as hematite/goethite
AI-generated identification · may be incorrectBrown to reddish-brown, granular and subtly sparkly, with earthy to weakly vitreous luster; likely Mohs hardness 6.5–7, massive texture, no obvious cleavage, and high density if iron-rich. The irregular pits and rusty coloring suggest weathering rather than a clean crystal or gemstone.
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Physical properties
Brown to reddish-brown, granular and subtly sparkly, with earthy to weakly vitreous luster; likely Mohs hardness 6.5–7, massive texture, no obvious cleavage, and high density if iron-rich. The irregular pits and rusty coloring suggest weathering rather than a clean crystal or gemstone.
Formation & geological history
Likely formed when quartz-rich sandstone was metamorphosed and later stained or cemented by iron oxides during weathering; the exact geological age cannot be determined from the photograph. Common in ancient metamorphic terrains and iron-bearing sedimentary formations.
Uses & applications
Used as durable crushed stone, aggregate, building stone, and occasionally as a decorative or lapidary material. This small rough piece has limited gem value.
Geological facts
Quartzite commonly scratches glass and resists weak acid; hematite-rich varieties may leave a reddish-brown streak. Identification is provisional because the image does not show a fresh surface or diagnostic tests.
Field identification & locations
Commonly found as rounded, resistant pebbles in stream gravels and exposed quartzite outcrops worldwide. Test with a steel nail or glass, inspect the streak, and use a magnet only if abundant magnetite is present.
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