sedimentary
Red Jasper
Silicon dioxide (SiO2) with iron oxide inclusions
Hardness: 6.5-7 (Mohs); Color: Brick red to deep terracotta; Luster: Dull to greasy; Crystal Structure: Microcrystalline (Trigonal); Cleavage: None (Conchoidal fracture); Specific Gravity: 2.58–2.91
- Hardness
- 6
- Color
- Brick red to deep terracotta
- Luster
- Dull to greasy
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Physical properties
Hardness: 6.5-7 (Mohs); Color: Brick red to deep terracotta; Luster: Dull to greasy; Crystal Structure: Microcrystalline (Trigonal); Cleavage: None (Conchoidal fracture); Specific Gravity: 2.58–2.91
Formation & geological history
Formed through the deposition of silica from hydrothermal solutions or volcanic ash in sedimentary environments where iron oxides (hematite) provide the red pigmentation. It can be found in rocks of various geological ages from Precambrian to recent times.
Uses & applications
Commonly used as a gemstone in jewelry (cabochons, beads), decorative ornaments, stone carvings, and lapidary art. Historically used for seals and amulets.
Geological facts
Ancient Egyptians associated red jasper with the blood of Isis and frequently carved it into protective amulets. It is an opaque variety of chalcedony that owes its color to high concentrations of iron.
Field identification & locations
Identify by its rich red color, extreme hardness (it will scratch glass), and smooth, shell-like conchoidal fracture pattern. Commonly found in riverbeds, deserts, and volcanic regions globally, including the USA, Brazil, and India.
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