sedimentary
Jasper
Silicon Dioxide (SiO2) with iron oxide inclusions
Hardness: 6.5-7 (Mohs). Color: Deep reddish-brown with a light-colored vein. Luster: Vitreous to waxy. Crystal Structure: Hexagonal (cryptocrystalline). Opaque with a smooth, almost greasy feel.
- Hardness
- 6
- Color
- Deep reddish-brown with a light-colored vein
- Luster
- Vitreous to waxy
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Physical properties
Hardness: 6.5-7 (Mohs). Color: Deep reddish-brown with a light-colored vein. Luster: Vitreous to waxy. Crystal Structure: Hexagonal (cryptocrystalline). Opaque with a smooth, almost greasy feel.
Formation & geological history
Formed when fine particulate materials, like volcanic ash or silica-rich water, consolidate under pressure in sedimentary or hydrothermal environments. Often occurs in association with iron ore deposits.
Uses & applications
Used primarily as a decorative stone, in jewelry (cabochons, beads), and for lapidary carving. Historically used for making tools due to its conchoidal fracture.
Geological facts
Jasper is a variety of chalcedony. The name comes from the Greek word 'iaspis', meaning 'spotted stone'. It was a favorite gem in the ancient world, mentioned in many historical texts and used in royal seals.
Field identification & locations
Identify by its high hardness (cannot be scratched by a steel nail), opacity, and smooth texture. Often found in riverbeds or as nodules in volcanic rock formations globally.
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