metamorphic
Iron-stained quartz-rich rock (likely ironstone/quartz vein material)
Quartz (SiO₂) with iron oxides/hydroxides, likely limonite/goethite; precise rock type cannot be confirmed visually
AI-generated identification · may be incorrectOpaque, rough and fractured, with cream-to-rust-brown coloring and a dull to slightly glassy luster. Quartz is Mohs 7; iron oxides are softer, and the specimen appears non-cleavable with irregular fracture.
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Physical properties
Opaque, rough and fractured, with cream-to-rust-brown coloring and a dull to slightly glassy luster. Quartz is Mohs 7; iron oxides are softer, and the specimen appears non-cleavable with irregular fracture.
Formation & geological history
Likely formed when silica-rich fluids deposited quartz in fractures, followed or accompanied by iron-rich weathering that stained the rock. Such veins occur in many geological ages and settings.
Uses & applications
Quartz-rich material is used in glass, aggregate, and silica products; iron oxides serve as pigments and iron ore when sufficiently concentrated. This rough specimen is primarily suited to collecting or display.
Geological facts
Rusty color commonly comes from goethite or limonite coating or mixing with quartz; color alone does not establish iron-ore grade.
Field identification & locations
Look for hard, glassy quartz areas that resist scratching by a steel knife, plus rusty coatings or veins. Quartz with iron staining is widespread in weathered outcrops and mineralized fractures worldwide.
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