sedimentary
Red Jasper (Chert)
Silicon Dioxide (SiO2) with Iron Oxide inclusions
Hardness: 6.5–7 on Mohs scale; Color: Deep brick red to brownish-red; Luster: Dull to vitreous; Crystal Structure: Microcrystalline/Cryptocrystalline (Hexagonal); Cleavage: None (conchoidal fracture); Specific Gravity: 2.58–2.91.
- Hardness
- 6
- Color
- Deep brick red to brownish-red
- Luster
- Dull to vitreous
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Physical properties
Hardness: 6.5–7 on Mohs scale; Color: Deep brick red to brownish-red; Luster: Dull to vitreous; Crystal Structure: Microcrystalline/Cryptocrystalline (Hexagonal); Cleavage: None (conchoidal fracture); Specific Gravity: 2.58–2.91.
Formation & geological history
Formed through the deposition of silica-rich fluids in volcanic or sedimentary environments, often associated with Banded Iron Formations (BIFs). The red color is derived from high concentrations of oxidized iron (hematite) during the lithification process.
Uses & applications
Extensively used as a gemstone for jewelry (cabochons, beads), decorative carvings, and as an ornamental stone in landscaping and interior design. Historically used for making tools and seals.
Geological facts
Jasper has been revered since antiquity; in the ancient world, it was known as the 'supreme nurturer.' It is a variety of chalcedony that is opaque due to the mineral impurities that give it its distinctive color patterns.
Field identification & locations
Identify in the field by its characteristic waxy to dull luster, lack of cleavage, and extreme hardness (it will scratch glass). Common locations include the Lake Superior region (USA), South Africa, India, and Brazil. Collectors should look for smooth, water-worn cobbles in riverbeds.
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