sedimentary
Jasper (Red/Brown)
Silicon Dioxide (SiO2) with iron oxide inclusions
Hardness: 6.5-7 on Mohs scale; Color: Reddish-brown to tan; Luster: Dull to waxy; Crystal Structure: Microcrystalline (trigonal); Cleavage: None/Conchoidal fracture.
- Hardness
- 6
- Color
- Reddish-brown to tan
- Luster
- Dull to waxy
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Physical properties
Hardness: 6.5-7 on Mohs scale; Color: Reddish-brown to tan; Luster: Dull to waxy; Crystal Structure: Microcrystalline (trigonal); Cleavage: None/Conchoidal fracture.
Formation & geological history
Formed from silica-rich fluids (often volcanic or hydrothermal in origin) that saturate sediment or volcanic ash, slowly precipitating microcrystalline quartz over millions of years.
Uses & applications
Commonly used for decorative lapidary work, cabochons for jewelry, small carvings, and as a component in aquarium gravel or landscaping.
Geological facts
Jasper is an opaque variety of chalcedony. Its name comes from the Greek word 'iaspis', meaning 'spotted stone.' It has been used by ancient civilizations for amulets and cylinder seals for thousands of years.
Field identification & locations
Identify in the field by its smooth, water-worn texture when found in riverbeds, its high hardness (it will scratch glass), and its completely opaque nature. Found globally, especially in Oregon, Idaho, and Western Australia.
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