Rock Identifier
Iron-rich jasper (possibly brecciated jasper) (Jasper, microcrystalline quartz (SiO₂) colored by iron oxides such as hematite and goethite) — mineral
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 incorrect

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.

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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.