sedimentary
Red Jasper (possibly banded Jaspilite)
Silicon Dioxide with Iron Oxide (SiO2 + Fe2O3)
Hardness: 6.5-7 (Mohs scale); Color: Deep red to reddish-brown with banding; Luster: Dull/Waxy; Crystal Structure: Microcrystalline (trigonal); Cleavage: None/Conchoidal fracture.
- Hardness
- 6
- Color
- Deep red to reddish-brown with banding
- Luster
- Dull/Waxy
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Physical properties
Hardness: 6.5-7 (Mohs scale); Color: Deep red to reddish-brown with banding; Luster: Dull/Waxy; Crystal Structure: Microcrystalline (trigonal); Cleavage: None/Conchoidal fracture.
Formation & geological history
Formed through the precipitation of silica from fluids, often in association with volcanic activity or hydrothermal vents. Red jasper specifically gets its color from high concentrations of iron inclusions. Many specimens date back to the Precambrian era.
Uses & applications
Used primarily for lapidary work, jewelry (cabochons), interior decoration, and as a popular collector's item due to its ability to take a high polish.
Geological facts
Jasper has been used as a gemstone since antiquity and is mentioned in various historical texts as a 'supreme nurturer.' It is a dense, opaque variety of chalcedony.
Field identification & locations
Identify in the field by its opacity (unlike translucent agate), waxy luster, and resistance to scratching from a steel knife. Commonly found in riverbeds, mountains, and as secondary deposits in volcanic rocks.
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