sedimentary (cryptocrystalline quartz)
Jasper (Tumbled)
Silicon Dioxide (SiO₂)
Hardness: 6.5–7 on Mohs scale; Color: Dark brown to reddish-brown; Luster: Vitreous to waxy; Crystal Structure: Hexagonal/Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific Gravity: 2.58–2.91
- Hardness
- 6
- Color
- Dark brown to reddish-brown
- Luster
- Vitreous to waxy
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Physical properties
Hardness: 6.5–7 on Mohs scale; Color: Dark brown to reddish-brown; Luster: Vitreous to waxy; Crystal Structure: Hexagonal/Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific Gravity: 2.58–2.91
Formation & geological history
Formed through the deposition of silica from water or hydrothermal fluids into cracks and cavities within rocks. Its opacity is due to high mineral impurities (often iron oxides). It can range from millions to over a billion years old depending on the host formation.
Uses & applications
Primarily used as a gemstone for jewelry, cabochons, and decorative items. In industry, it is sometimes used as an abrasive or in construction as a sturdy, weather-resistant aggregate.
Geological facts
Jasper is of ancient historical significance; it was mentioned in Greek and Roman texts and used by early humans for tools because of its hardness. Its name comes from the Greek word 'iaspis', meaning 'spotted stone'.
Field identification & locations
Identify in the field by its hardness (it will scratch glass) and its complete opacity—unlike agate, it does not let light pass through. Commonly found in riverbeds, beaches, and desert regions worldwide, particularly in areas with volcanic or sedimentary deposits.
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