sedimentary
Jasper (Red Jasper)
Silicon Dioxide (SiO2) with iron oxide inclusions
Hardness: 6.5-7 (Mohs scale). Color: Earthy red, brown, or brownish-red. Luster: Dull to vitreous, waxy when polished. Crystal Structure: Trigonal (microcrystalline/cryptocrystalline). Cleavage: None (conchoidal fracture). Specific Gravity: 2.58-2.91.
- Hardness
- 6
- Color
- Earthy red, brown, or brownish-red
- Luster
- Dull to vitreous, waxy when polished
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Physical properties
Hardness: 6.5-7 (Mohs scale). Color: Earthy red, brown, or brownish-red. Luster: Dull to vitreous, waxy when polished. Crystal Structure: Trigonal (microcrystalline/cryptocrystalline). Cleavage: None (conchoidal fracture). Specific Gravity: 2.58-2.91.
Formation & geological history
Formed through the deposition of silica from mineral springs or hydrothermal veins. The red color is typically due to iron (hematite) inclusions within the cryptocrystalline quartz. It can occur in volcanic or sedimentary environments and can range from Precambrian to recent geological eras.
Uses & applications
Commonly used as a gemstone for jewelry (cabochons, beads), decorative ornaments, stone carvings, and lapidary practice. Historically used for making tools and seals.
Geological facts
In antiquity, jasper was considered a 'rain bringer' and was used in breastplates of high priests. Red jasper is often called 'the stone of endurance' in metaphysical circles. It is virtually entirely opaque, distinguishing it from translucent varieties of chalcedony like carnelian.
Field identification & locations
Identify in the field by its opacity, conchoidal (shell-like) fracture, and hardness (it will scratch glass but cannot be scratched by a steel knife). Commonly found in the Western United States (Oregon, Idaho, California), India, Brazil, and South Africa.
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