sedimentary
Red Jasper
Silicon dioxide (SiO2) with iron oxide inclusions
Hardness: 6.5-7 Mohs; Color: Brick red to brownish red; Luster: Dull to vitreous; Crystal Structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific Gravity: 2.58-2.91
- Hardness
- 6
- Color
- Brick red to brownish red
- Luster
- Dull to vitreous
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Physical properties
Hardness: 6.5-7 Mohs; Color: Brick red to brownish red; Luster: Dull to vitreous; Crystal Structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific Gravity: 2.58-2.91
Formation & geological history
Formed through the deposition of silica-rich sediments in deep sea environments or through the infiltration of silica-rich fluids in volcanic ash or other porous rocks. The red color is derived from high hematite (iron oxide) inclusions.
Uses & applications
Commonly used for lapidary work, cabochons, beads for jewelry, ornamental carvings, and as a decorative stone in landscaping. Historically used for weapons and tools due to its conchoidal fracture.
Geological facts
Red Jasper has been used by many ancient civilizations; the Ancient Egyptians associated it with the blood of Isis. It is a variety of chalcedony that is opaque due to its high mineral impurity content.
Field identification & locations
Identify in the field by its deep red color, extreme hardness (it will scratch glass), and smooth, shell-like fracture surfaces. Frequently found in stream beds or as rounded pebbles on beaches in volcanic regions.
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