metamorphic
Iron-rich quartzite or limonite-bearing rock
Quartzite (SiO₂) with iron oxides/hydroxides, chiefly hematite and goethite
AI-generated identification · may be incorrectBrown to reddish-brown, earthy to subvitreous luster, irregular fracture, and apparently granular/fibrous texture. Quartzite has Mohs hardness about 7; iron-stained portions may be softer and have a specific gravity roughly 2.6–4.3.
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Physical properties
Brown to reddish-brown, earthy to subvitreous luster, irregular fracture, and apparently granular/fibrous texture. Quartzite has Mohs hardness about 7; iron-stained portions may be softer and have a specific gravity roughly 2.6–4.3.
Formation & geological history
Likely metamorphosed quartz-rich sandstone later altered or cemented by oxidized iron-bearing fluids. Exact age and locality cannot be determined from the photograph.
Uses & applications
Common quartzite is used as aggregate, building stone, and sometimes decorative rock; iron-rich pieces are mainly collected as mineral specimens. Jewelry use is limited unless the material polishes attractively.
Geological facts
The red-brown coloration is typically produced by hematite or goethite coatings between quartz grains, rather than by a uniformly colored mineral. A streak test and hardness test would substantially improve identification.
Field identification & locations
Look for abundant quartz grains that resist scratching glass, a pale-to-reddish streak, and little or no cleavage; a strong magnet response would suggest magnetite instead. Common in metamorphic belts and iron-rich weathering zones.
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