metamorphic

Iron-stained quartz-rich rock, likely quartzite or silicified sandstone

Quartzite (dominantly SiO₂), with hematite/goethite surface staining

AI-generated identification · may be incorrect

White to pale gray, massive and granular, with a rusty red-brown coating from iron oxides; likely Mohs hardness 6.5–7, vitreous to dull luster, little or no cleavage, and specific gravity around 2.6. The exposed brown material may be hematite, goethite, or weathered iron-rich cement rather than a separate mineral layer…

Identified August 31, 2026More metamorphic →

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Physical properties

Formation & geological history

Probably formed when quartz-rich sandstone was metamorphosed and recrystallized, then weathered and stained by oxidizing groundwater; exact age and geological setting cannot be determined from the image. If it is unaltered sandstone, it would instead be sedimentary.

Uses & applications

Common quartzite is used as crushed stone, aggregate, riprap, and occasionally dimension stone; attractive pieces may be collected as specimens. It has little jewelry value unless the iron pattern is unusually distinctive or the material takes a good polish.

Geological facts

The red-brown color is characteristic of hematite/goethite (“iron oxide”) weathering. Quartzite typically breaks across grains rather than around them and can scratch ordinary glass.

Field identification & locations

Look for a sugary quartz texture, very hard fracture, and resistance to scratching; a dilute acid test should show no reaction. Common in quartz-rich metamorphic terrains and gravel deposits.