metamorphic

Iron-stained quartz-bearing rock, possibly quartzite

Quartzite (mostly SiO₂), with iron-oxide minerals such as hematite/goethite

AI-generated identification · may be incorrect

Hardness about 7 Mohs; irregular, granular fracture; vitreous to earthy luster; brown, gray, and rusty-yellow coloration from iron staining. Individual quartz crystals are poorly visible, and no reliable cleavage is apparent.

Identified September 5, 2026More metamorphic →

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Physical properties

Formation & geological history

Likely formed when quartz-rich sandstone was metamorphosed and recrystallized under elevated heat and pressure, commonly during mountain-building events; its exact geological age cannot be determined from the photograph.

Uses & applications

Quartzite is used as crushed stone, building and decorative stone, and occasionally as a lapidary material. This rough specimen has modest collector value unless it has unusual mineralization or provenance.

Geological facts

The rusty colors indicate oxidation of iron-bearing minerals, while the hard, quartz-rich matrix resists scratching by a steel knife. It could also be an iron-rich quartz vein or altered sandstone rather than true quartzite.

Field identification & locations

Common in metamorphic belts worldwide, including the Appalachian, Rocky, and European mountain regions. Confirm by testing whether it scratches glass, checking for abundant interlocking quartz grains, and inspecting a fresh surface; value is typically $2–$15 for an ordinary hand specimen, or $20–$75 with attractive mineralization.