sedimentary
Red Jasper (Chert)
Silicon Dioxide (SiO2) with iron oxide inclusions
Hardness: 6.5-7 on Mohs scale. Color: Opaque rusty red to brownish-red. Luster: Dull to vitreous/waxy. Crystal structure: Microcrystalline/Trigonal (Cryptocrystalline). Cleavage: None, exhibits conchoidal fracture.
- Hardness
- 6
- Color
- Opaque rusty red to brownish-red
- Luster
- Dull to vitreous/waxy
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Physical properties
Hardness: 6.5-7 on Mohs scale. Color: Opaque rusty red to brownish-red. Luster: Dull to vitreous/waxy. Crystal structure: Microcrystalline/Trigonal (Cryptocrystalline). Cleavage: None, exhibits conchoidal fracture.
Formation & geological history
Formed primarily through the accumulation of silica-rich fluids in sedimentary environments or as a replacement mineral in volcanic ash. The red color is caused by high concentrations of hematite (iron) during formation.
Uses & applications
Used extensively as a gemstone, in jewelry (cabochons, beads), for decorative carvings, and in lapidary arts. Historically used for making tools due to its sharp conchoidal fracture.
Geological facts
Jasper was a favorite gem in the ancient world, mentioned in many cultural myths and religious texts. It is known as the 'Supreme Nurturer' in metaphysical circles. Red jasper in particular is often associated with Banded Iron Formations (BIFs).
Field identification & locations
Identify by its smooth, shell-like (conchoidal) break, opaque appearance, and inability to be scratched by a steel knife. Commonly found in riverbeds, deserts, and coastal areas where volcanic and sedimentary rocks interact.
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