metamorphic
Iron-stained quartz-rich rock (likely limonite-bearing quartzite)
Quartzite, predominantly quartz (SiO₂), with iron oxides/hydroxides such as limonite/goethite
AI-generated identification · may be incorrectBrown to ochre, rough and granular with rusty staining; quartz has Mohs hardness 7 and vitreous luster, while iron coatings are dull. The photo does not show enough detail to confirm texture or mineral proportions.
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Physical properties
Brown to ochre, rough and granular with rusty staining; quartz has Mohs hardness 7 and vitreous luster, while iron coatings are dull. The photo does not show enough detail to confirm texture or mineral proportions.
Formation & geological history
Quartz-rich sandstone may be metamorphosed into quartzite, while iron-bearing fluids or weathering produce the ochre coating. Its age and exact formation environment cannot be determined from the image.
Uses & applications
Similar material is used as aggregate, landscaping stone, and sometimes building stone; this specimen appears primarily of modest collecting interest.
Geological facts
The rusty color commonly comes from iron oxides rather than the main rock-forming mineral. Quartzite is typically very hard and resists scratching by a steel knife.
Field identification & locations
Look for interlocking quartz grains and a hardness that can scratch glass; iron staining alone is not diagnostic. Quartzite occurs worldwide, but a closer examination or scratch test is needed to identify this specimen confidently.
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