metamorphic

Iron-stained quartzite or quartz-rich sandstone

Quartzite; predominantly quartz (SiO₂) with iron-oxide staining

AI-generated identification · may be incorrect

Hardness about 7 Mohs; off-white to pale gray with orange-red hematite/goethite staining, dull to sugary/vitreous luster, and no obvious cleavage. The granular texture suggests interlocking quartz grains, though a weathered sandstone is also possible.

Identified September 8, 2026More metamorphic →

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Physical properties

Formation & geological history

Likely formed when quartz-rich sandstone was metamorphosed and recrystallized during burial or tectonic heating; iron-bearing groundwater later produced the orange staining. Exact geological age cannot be determined from the image.

Uses & applications

Common quartzite is used as aggregate, riprap, building stone, and decorative material; attractive pieces may be collected, but this small specimen has little commercial value.

Geological facts

Quartzite commonly fractures across grains rather than around them and can scratch ordinary glass. The orange coloration is typically caused by oxidized iron minerals, not by the quartz itself.

Field identification & locations

Test with a steel knife or glass: genuine quartzite resists scratching, while sandstone may crumble or scratch more easily. Common sources include metamorphic belts worldwide, especially the Appalachian, Rocky Mountain, and Precambrian shield regions.