metamorphic
Iron-stained quartz-rich rock (likely quartzite or quartz vein material)
Quartz (SiO₂), commonly with limonite/goethite iron oxides; possible quartzite matrix
AI-generated identification · may be incorrectWhite to gray, brown-orange iron staining, vitreous to dull luster, massive interlocking quartz grains with no obvious cleavage. Quartz hardness is 7 Mohs; specific gravity about 2.65, though porous staining and matrix may vary.
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Physical properties
White to gray, brown-orange iron staining, vitreous to dull luster, massive interlocking quartz grains with no obvious cleavage. Quartz hardness is 7 Mohs; specific gravity about 2.65, though porous staining and matrix may vary.
Formation & geological history
Likely formed from silica-rich material recrystallized during metamorphism, or from hydrothermal quartz filling a fracture; later oxidation produced the brown limonite/goethite staining. Precise age and locality cannot be determined from the photograph.
Uses & applications
Used as aggregate, decorative stone, and occasionally as a lapidary material; attractive translucent portions may be polished, but this specimen appears mainly collectible rather than gem-quality.
Geological facts
The orange-brown color is typically caused by hydrated iron oxides rather than by the quartz itself. A fresh broken surface should be glassy or granular and may show translucent quartz.
Field identification & locations
Common in quartz veins and metamorphic terrains worldwide. Test with a steel file or glass: quartz should scratch glass and resist a steel blade; dilute hydrochloric acid should not visibly fizz.
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