sedimentary
Jasper (Red and Tan Jasper)
Microcrystalline Quartz (SiO2) with iron oxide inclusions
Hardness: 6.5-7 Mohs; Color: Mottle red, tan, and brown; Luster: Vitreous to waxy (especially when wet or polished); Crystal Structure: Hexagonal (cryptocrystalline); Cleavage: None (conchoidal fracture)
- Hardness
- 6
- Color
- Mottle red, tan, and brown
- Luster
- Vitreous to waxy (especially when wet or polished)
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Physical properties
Hardness: 6.5-7 Mohs; Color: Mottle red, tan, and brown; Luster: Vitreous to waxy (especially when wet or polished); Crystal Structure: Hexagonal (cryptocrystalline); Cleavage: None (conchoidal fracture)
Formation & geological history
Formed when silica-rich fluids permeate through volcanic ash or sedimentary rocks, precipitating microcrystalline quartz. The coloration is due to iron impurities. Common in ancient volcanic or river-deposited environments.
Uses & applications
Mainly used for lapidary work, jewelry (cabochons), ornamental stone carving, and as high-quality aquarium/garden decor.
Geological facts
Jasper is an opaque variety of chalcedony. The name 'jasper' comes from the Greek word for 'spotted stone'. It was highly prized in the ancient world for its supposed healing powers.
Field identification & locations
Identify by its opacity, smooth texture, and inability to be scratched by a steel knife. Frequently found as water-worn river pebbles or in gravel beds along coastlines.
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