igneous
Quartz-rich breccia or vein quartz with iron staining
Microcrystalline to crystalline SiO₂, likely quartz with iron oxides/hydroxides and altered host rock
AI-generated identification · may be incorrectWhite to translucent quartz forms irregular massive patches, with brown-red limonite/goethite staining and darker matrix; vitreous luster, no obvious cleavage, Mohs hardness about 7, specific gravity near 2.65.
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Physical properties
White to translucent quartz forms irregular massive patches, with brown-red limonite/goethite staining and darker matrix; vitreous luster, no obvious cleavage, Mohs hardness about 7, specific gravity near 2.65.
Formation & geological history
Likely formed when silica-rich hydrothermal fluids filled fractures, followed by brecciation and oxidation of iron-bearing minerals near the surface; precise age and locality cannot be determined from the photograph.
Uses & applications
Used decoratively as lapidary material, cabochons, and display specimens; generally unsuitable for construction unless part of a larger quarry deposit.
Geological facts
The brown coloration is commonly weathering-derived iron oxide rather than the primary quartz color. A steel file should not scratch fresh quartz, while quartz can scratch ordinary glass.
Field identification & locations
Common in hydrothermal veins and silicified zones worldwide, including quartz-vein districts and iron-stained outcrops. Confirm with a hardness test, streak test on unglazed porcelain, and ideally acid or mineralogical testing of the dark matrix.
