mineral
Iron-rich jasper (possibly brecciated jasper)
Jasper, microcrystalline quartz (SiO₂) colored by iron oxides such as hematite and goethite
AI-generated identification · may be incorrectHardness about 6.5–7 Mohs; opaque red, orange, brown, and black coloration with a dull to waxy or locally vitreous luster. It is cryptocrystalline, lacks visible cleavage, and commonly fractures conchoidally; specific gravity is roughly 2.5–2.8.
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Physical properties
Hardness about 6.5–7 Mohs; opaque red, orange, brown, and black coloration with a dull to waxy or locally vitreous luster. It is cryptocrystalline, lacks visible cleavage, and commonly fractures conchoidally; specific gravity is roughly 2.5–2.8.
Formation & geological history
Forms when silica-rich fluids cement and replace volcanic or sedimentary material, with iron oxidation producing the vivid colors; individual deposits range from Precambrian to Cenozoic. The specimen appears heavily iron-stained and possibly brecciated or weathered.
Uses & applications
Used as a lapidary stone for cabochons, carvings, beads, and polished slabs; massive material has limited industrial value compared with ordinary quartz.
Geological facts
Jasper is an opaque variety of chalcedony or microcrystalline quartz, and color patterns are often diagnostic of its locality. Red tones typically reflect hematite, while yellow-brown zones commonly contain goethite or limonite.
Field identification & locations
Identify it by its opaque, fine-grained texture, high hardness, earthy iron colors, and lack of cleavage; it should scratch glass but not be scratched by a steel knife easily. Common in volcanic terrains and iron-rich sedimentary formations worldwide, including the western United States, Australia, India, and Brazil.
