
sedimentary
Red Jasper
Jasper (Silicate mineral - SiO2)
Hardness: 6.5-7 Mohs; Color: Opaque brick red; Luster: Dull to vitreous; Crystal Structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific Gravity: 2.58-2.91
- Hardness
- 6
- Color
- Opaque brick red
- Luster
- Dull to vitreous
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Physical properties
Hardness: 6.5-7 Mohs; Color: Opaque brick red; Luster: Dull to vitreous; Crystal Structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific Gravity: 2.58-2.91
Formation & geological history
Formed through the infiltration of silica in sedimentary rocks or volcanic ash. The red color is caused by high concentrations of iron oxide (hematite) inclusions during the solidification process.
Uses & applications
Commonly used for lapidary work, cabochons, beads for jewelry, ornamental carvings, and as a popular specimen for rock tumbling and metaphysical collections.
Geological facts
Jasper has been used as a gemstone since antiquity; it is mentioned in the Bible and was favored in ancient Mesopotamia for cylinder seals. It is a variety of chalcedony.
Field identification & locations
Identify in the field by its opacity (it does not transmit light even on thin edges), its red streak on a streak plate, and its smooth, shell-like fracture pattern. Often found in riverbeds and desert environments.
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