mineral

Iron-stained quartz specimen

Quartz (SiO₂) with iron-oxide staining, likely limonite/goethite

AI-generated identification · may be incorrect

Opaque to translucent gray-brown, earthy to vitreous luster, irregular fracture; quartz has Mohs hardness 7 and trigonal crystal structure. The image does not show enough detail to confirm a specific mineral or crystal habit.

Identified September 23, 2026More mineral →

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Physical properties

Formation & geological history

Quartz commonly forms in veins and cavities as silica-rich fluids cool; iron oxides can later stain or coat it during weathering. Its age and exact formation environment cannot be determined from the photograph.

Uses & applications

Mostly a modest collecting specimen; quartz is also used in glass, electronics, and abrasives, while iron oxides are used as pigments and ores.

Geological facts

Brown and rusty colors commonly result from iron oxides coating or filling fractures in otherwise pale quartz.

Field identification & locations

Look for hardness near 7, which allows quartz to scratch glass, and for irregular, non-cleavage fracture surfaces. Similar iron-stained quartz occurs worldwide in veins and weathered outcrops.