sedimentary
Jasper (specifically Red Jasper or Iron-stained Chert)
Silicon dioxide (SiO2) with iron oxide inclusions
Hardness: 6.5-7 on the Mohs scale; Color: Reddish-orange to brownish-red; Luster: Dull to vitreous; Crystal Structure: Microcrystalline/Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.58-2.91
- Hardness
- 6
- Color
- Reddish-orange to brownish-red
- Luster
- Dull to vitreous
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Physical properties
Hardness: 6.5-7 on the Mohs scale; Color: Reddish-orange to brownish-red; Luster: Dull to vitreous; Crystal Structure: Microcrystalline/Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.58-2.91
Formation & geological history
Formed through the deposition of silica-rich fluids in volcanic ash or sedimentary beds. The red color is typically the result of iron oxidation occurring during the diagenesis process, often dating back to the Proterozoic or Paleozoic eras depending on the specific deposit.
Uses & applications
Used primarily as a gemstone for lapidary work (cabochons, beads), decorative carvings, and occasionally as an industrial abrasive or aggregate in construction. It is highly valued in the metaphysical and rock-collecting communities.
Geological facts
Jasper is an opaque variety of chalcedony. Historically, it was known as the 'supreme nurturer' in ancient cultures and was used in the breastplate of the High Priest in biblical times. It is famous for its wide variety of banding and patterns caused by different mineral impurities.
Field identification & locations
Identify in the field by its waxy-to-dull luster, conchoidal (shell-like) fracture edges, and extreme hardness (it will scratch glass). It is commonly found in riverbeds, desert pavements, and near volcanic regions in places like the Western USA, Brazil, and India.
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