sedimentary
Brown Jasper
Silicon Dioxide (SiO2) with iron oxide impurities
Hardness: 6.5-7 (Mohs); Color: Chocolate brown; Luster: Vitreous to dull; Crystal structure: Trigonal (microcrystalline); Cleavage: None/Conchoidal fracture; Specific gravity: 2.58-2.91
- Hardness
- 6
- Color
- Chocolate brown
- Luster
- Vitreous to dull
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Physical properties
Hardness: 6.5-7 (Mohs); Color: Chocolate brown; Luster: Vitreous to dull; Crystal structure: Trigonal (microcrystalline); Cleavage: None/Conchoidal fracture; Specific gravity: 2.58-2.91
Formation & geological history
Formed via the deposition of silica from water or during volcanic processes. It occurs as nodules or in cracks, taking millions of years to solidify into chert/jasper forms.
Uses & applications
Used primarily for lapidary work, jewelry (cabochons), talismans, and as polished decorative stones.
Geological facts
The brown color is typically caused by goethite or iron oxide. Jasper is an opaque variety of chalcedony. Historically, it was known as a 'nurturing stone' in ancient cultures.
Field identification & locations
Identify by its high hardness (doesn't scratch with a steel knife), smooth conchoidal fracture, and absolute opacity. Commonly found in riverbeds and arid regions globally.
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