metamorphic
Iron-stained quartz-rich rock, likely weathered quartzite
Quartzite (dominantly quartz, SiO₂), with iron-oxide minerals such as hematite/goethite
AI-generated identification · may be incorrectHardness about 7 for quartz; typically gray, white, tan, and rusty brown, with a granular texture and glassy to dull luster. The dark brown and orange areas are likely iron-oxide staining or replacement; no clear crystal cleavage is visible.
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Physical properties
Hardness about 7 for quartz; typically gray, white, tan, and rusty brown, with a granular texture and glassy to dull luster. The dark brown and orange areas are likely iron-oxide staining or replacement; no clear crystal cleavage is visible.
Formation & geological history
Likely formed when quartz-rich sandstone was metamorphosed and recrystallized, then exposed to weathering that oxidized iron-bearing minerals. Its precise geological age cannot be determined from the photograph.
Uses & applications
Useful as crushed aggregate, road stone, building and decorative stone; attractive iron-stained pieces may be collected, though this specimen appears primarily a field sample rather than gem material.
Geological facts
Quartzite commonly breaks across grains rather than around them and can be harder than the steel of a knife. Rust-colored zones indicate oxidation, commonly involving hematite or goethite.
Field identification & locations
Common in metamorphic mountain belts worldwide. Test with a steel nail or knife: quartzite should resist scratching; a streak test on an unweathered surface should generally be white, while iron oxides may produce yellow-brown to reddish streaks.
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