sedimentary
Red Jasper
Silicon Dioxide (SiO2) with Hematite inclusions
Hardness: 6.5–7 (Mohs scale); Color: Deep brick red to brownish-red; Luster: Vitreous to waxy (especially when polished); Crystal Structure: Hexagonal (trigonal) microcrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.58–2.91
- Hardness
- 6
- Color
- Deep brick red to brownish-red
- Luster
- Vitreous to waxy (especially when polished)
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Physical properties
Hardness: 6.5–7 (Mohs scale); Color: Deep brick red to brownish-red; Luster: Vitreous to waxy (especially when polished); Crystal Structure: Hexagonal (trigonal) microcrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.58–2.91
Formation & geological history
Formed through the accumulation of silica-rich micro-organisms or volcanic ash within sedimentary environments. The red pigmentation is caused by iron (hematite) inclusions that diffused through the silica during diagenesis or hydrothermal activity.
Uses & applications
Used primarily in lapidary work for cabochons, beads, and tumbled stones. Historically used for seal stones, ornaments, and inlay work. Valued in metaphysical circles as a grounding stone.
Geological facts
Jasper was a favorite gem in the ancient world, mentioned in biblical texts and used by Ancient Egyptians for amulets. It is an opaque variety of chalcedony, meaning light does not pass through it even on thin edges.
Field identification & locations
Identify in the field by its opaque nature (unlike translucent carnelian), its high hardness (it will scratch glass), and its distinctive dull, earthy luster on raw surfaces. Commonly found in riverbeds or as nodules in volcanic rock in regions like Brazil, India, and the United States (Southwest and Pacific Northwest).
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