metamorphic
Polished iron-stained quartz/quartzite
Quartz (SiO₂), likely quartzite or massive vein quartz with iron-oxide staining
AI-generated identification · may be incorrectWhite to pale gray, translucent patches with brown-red earthy limonite/goethite inclusions; vitreous to waxy luster and irregular fracture. Quartz hardness is 7 Mohs; quartzite is granular and very resistant, while cleavage is absent; specific gravity about 2.65.
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Physical properties
White to pale gray, translucent patches with brown-red earthy limonite/goethite inclusions; vitreous to waxy luster and irregular fracture. Quartz hardness is 7 Mohs; quartzite is granular and very resistant, while cleavage is absent; specific gravity about 2.65.
Formation & geological history
Likely silica-rich vein material or quartzite later stained by circulating, oxygen-rich groundwater depositing iron oxides. The precise age and locality cannot be determined from the photograph.
Uses & applications
Primarily a lapidary, decorative, or teaching specimen; attractive pieces may be tumbled, polished, or cut into cabochons, but this appearance has little industrial or gem value.
Geological facts
The brown coloration is probably limonite/goethite rather than a separate brown mineral. A streak test, hardness test, and close examination of grain boundaries would help distinguish quartzite from massive vein quartz.
Field identification & locations
Common in quartz veins, weathered metamorphic terrains, and iron-rich soils worldwide; quartz should scratch ordinary glass, while the brown coating may crumble or leave a yellow-brown streak. Avoid relying on color alone for identification.
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