metamorphic
Iron-stained quartz-rich rock, possibly ferruginous quartzite
Quartz-rich ferruginous rock; exact lithology cannot be determined from the image alone
AI-generated identification · may be incorrectRust-red to brown iron-oxide coating with pale, glassy-to-granular quartz. If quartzite, quartz hardness is about 7 Mohs, vitreous luster, and no cleavage; specimen texture and density vary with iron content.
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Physical properties
Rust-red to brown iron-oxide coating with pale, glassy-to-granular quartz. If quartzite, quartz hardness is about 7 Mohs, vitreous luster, and no cleavage; specimen texture and density vary with iron content.
Formation & geological history
Likely formed when iron-bearing fluids oxidized and stained a quartz-rich rock; if metamorphosed sandstone, its grains were fused during burial and heating. Its age and precise formation environment cannot be established visually.
Uses & applications
Quartzite may be used as crushed aggregate, building stone, or occasionally as a decorative specimen; these rough pieces are mainly suitable for collecting.
Geological facts
The rusty color commonly comes from iron oxides such as hematite or goethite, rather than from the quartz itself.
Field identification & locations
Look for hard, gritty-to-glassy quartz grains and rusty staining; quartz should scratch glass, while iron-rich areas may be more crumbly. Similar material occurs widely in weathered iron-bearing formations; identification would benefit from a fresh break and hardness test.
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