sedimentary
Jasper
Silicon dioxide (SiO2) with impurities
Hardness: 6.5-7 (Mohs scale), Color: Green with brown/red banding, Luster: Vitreous to waxy, Crystal structure: Hexagonal (cryptocrystalline), Cleavage: None (conchoidal fracture), Specific Gravity: 2.58-2.91
- Hardness
- 6
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Physical properties
Hardness: 6.5-7 (Mohs scale), Color: Green with brown/red banding, Luster: Vitreous to waxy, Crystal structure: Hexagonal (cryptocrystalline), Cleavage: None (conchoidal fracture), Specific Gravity: 2.58-2.91
Formation & geological history
Formed through the accumulation of fine siliceous material in volcanic ash or sedimentary deposits, often cemented by silica under low heat and pressure over millions of years.
Uses & applications
Used primarily in lapidary work for jewelry, cabochons, and decorative carvings; also a popular stone for tumbling and collecting.
Geological facts
Jasper is an opaque variety of chalcedony. The name comes from the Greek word 'iaspis', meaning 'spotted stone'. It has been used for thousands of years, with archaeological evidence of its use in bow drills in the Neolithic era.
Field identification & locations
Identify in the field by its hardness (it will scratch glass), opaque nature, and smooth, waxy surface when polished or water-worn. Common in riverbeds and coastal areas worldwide.
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