metamorphic
Iron-rich quartzite or weathered ironstone
Quartzite dominated by quartz (SiO₂), with iron oxides/hydroxides such as hematite and goethite
AI-generated identification · may be incorrectHardness about 6.5–7; rusty brown, orange, gray, and metallic-looking patches; generally nonmetallic to locally submetallic luster, granular texture, and no obvious cleavage. The surface appears heavily weathered and iron-stained.
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Physical properties
Hardness about 6.5–7; rusty brown, orange, gray, and metallic-looking patches; generally nonmetallic to locally submetallic luster, granular texture, and no obvious cleavage. The surface appears heavily weathered and iron-stained.
Formation & geological history
Likely formed when quartz-rich sandstone was metamorphosed into quartzite, followed by oxidation and weathering that concentrated iron minerals; its precise age cannot be determined from the photograph. Common in Precambrian and other ancient metamorphic terrains.
Uses & applications
Used as aggregate, building stone, and occasionally ornamental material; ordinary pieces have little jewelry value unless unusually attractive or mineral-rich.
Geological facts
Quartzite commonly scratches glass and resists weak acid, while iron staining produces red-brown colors. The specimen may also be a silicified ironstone, which requires a fresh surface or testing for confident distinction.
Field identification & locations
Look for a very hard, fused quartz-grain texture and rusty coatings; a steel nail should not scratch it, and a magnet may detect magnetite if present. Common in metamorphic belts, hillsides, and gravel deposits.
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