metamorphic

Iron-rich quartzite or ferruginous sandstone

Quartzite dominated by quartz (SiO₂), stained by hematite/goethite (Fe₂O₃/FeOOH)

AI-generated identification · may be incorrect

Granular, reddish-brown to gray, with a dull to sugary vitreous luster; quartz grains are tightly fused, and iron oxides create the red coating and matrix. Hardness is about 6.5–7 Mohs, with no prominent cleavage and specific gravity roughly 2.6–2.8.

Identified September 20, 2026More metamorphic →

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Physical properties

Formation & geological history

Likely quartz-rich sandstone altered by burial and heat, then stained or cemented by iron-bearing fluids; commonly Precambrian to younger, but age cannot be determined from the photograph.

Uses & applications

Used as durable crushed stone, building or paving material, and occasionally as a decorative stone; attractive pieces may be collected but are generally low-value.

Geological facts

The red color is typically caused by hematite, while darker brown or yellow areas may contain goethite or limonite. Strongly fused quartzite will scratch ordinary glass and resist crumbling when struck.

Field identification & locations

Look for visible quartz grains, very high hardness, and a lack of fizz with dilute hydrochloric acid; sandstone generally breaks around grains, whereas quartzite fractures through them. Common in metamorphic terrains worldwide, including India, Brazil, Australia, and the United States.