sedimentary
Red Jasper (Chert)
Silicon Dioxide (SiO2) with iron inclusions
Hardness: 6.5-7 Mohs; Color: Brick red to brownish-red; Luster: Dull to waxy; Crystal structure: Microcrystalline/Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific gravity: 2.58-2.91
- Hardness
- 6
- Color
- Brick red to brownish-red
- Luster
- Dull to waxy
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Physical properties
Hardness: 6.5-7 Mohs; Color: Brick red to brownish-red; Luster: Dull to waxy; Crystal structure: Microcrystalline/Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific gravity: 2.58-2.91
Formation & geological history
Formed when silica-rich fluids permeate through sedimentary or volcanic rock, often in hydrothermal environments. The red color comes from iron oxide (hematite) inclusions incorporated during the formation process.
Uses & applications
Used primarily as decorative stone, in lapidary work for cabochons and beads, and as an ornamental gemstone. Historically used for making tools due to its conchoidal fracture.
Geological facts
Jasper has been used by ancient civilizations for seals and jewelry for thousands of years. It is a variety of chalcedony that is opaque due to high mineral content.
Field identification & locations
Identify by its characteristic red color, extreme hardness (it will scratch glass), and smooth, curved fracture surfaces. Commonly found in riverbeds and coastal areas worldwide.
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