igneous
Iron-stained quartz-rich rock
Likely quartz with iron oxides/hydroxides (goethite and/or limonite); exact rock type cannot be determined from the image
AI-generated identification · may be incorrectOpaque, rough, tan to rusty-brown with pale quartz-rich patches and a small cavity. Quartz has Mohs hardness 7, vitreous luster, and hexagonal crystal structure; iron staining is earthy to dull.
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Physical properties
Opaque, rough, tan to rusty-brown with pale quartz-rich patches and a small cavity. Quartz has Mohs hardness 7, vitreous luster, and hexagonal crystal structure; iron staining is earthy to dull.
Formation & geological history
Likely formed when silica-rich rock or vein material was altered and stained by iron-bearing fluids or weathering. Its age and precise formation setting are not identifiable from appearance alone.
Uses & applications
Primarily a field or collection specimen; iron-rich material may be an ore indicator, while quartz has broad industrial uses.
Geological facts
Rusty colors commonly come from iron oxides such as goethite or limonite coating or replacing other minerals.
Field identification & locations
Look for hardness: quartz should scratch glass and resist a steel knife; a streak test may reveal yellow-brown iron oxides. Similar material occurs in weathered quartz veins and iron-rich outcrops worldwide.
