metamorphic

Iron-stained quartzite (ferruginous quartzite)

Quartzite, chiefly SiO₂, colored by iron oxides/hydroxides such as hematite and goethite

AI-generated identification · may be incorrect

Hardness about 7 Mohs; reddish-brown, gray, and black coloration; typically vitreous to dull luster, massive granular texture, and no prominent cleavage. The rusty red zones are iron-oxide staining or cement.

Identified September 6, 2026More metamorphic →

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Physical properties

Formation & geological history

Formed when quartz-rich sandstone was deeply buried and recrystallized during metamorphism; iron-bearing fluids later produced the red-brown staining. Its exact geological age and locality cannot be determined from the image.

Uses & applications

Used as crushed stone, road aggregate, building stone, and decorative landscape material; attractive pieces may be collected or cut for cabochons, though this specimen appears primarily ornamental.

Geological facts

Quartzite is tougher and generally more resistant to weathering than its sandstone precursor. A strong reddish streak or magnetic response, if present, may indicate abundant hematite or magnetite rather than pure quartzite.

Field identification & locations

Identify it by its very hard, quartz-rich texture and granular fracture; it should scratch glass and resist a steel knife. Common in metamorphic mountain belts worldwide, including India, Brazil, the United States, and Scandinavia.