sedimentary
Jasper (specifically Red Jasper)
Silicon Dioxide with Iron Oxides (SiO2 + Fe2O3)
Hardness: 6.5 - 7 on the Mohs scale; Color: Brick red to brownish-red with dark grey streaks; Luster: Dull to waxy; Crystal structure: Microcrystalline/Cryptocrystalline (Trigonal); Cleavage: None (Conchoidal fracture); Specific gravity: 2.58 - 2.91
- Hardness
- 6
- Color
- Brick red to brownish-red with dark grey streaks
- Luster
- Dull to waxy
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Physical properties
Hardness: 6.5 - 7 on the Mohs scale; Color: Brick red to brownish-red with dark grey streaks; Luster: Dull to waxy; Crystal structure: Microcrystalline/Cryptocrystalline (Trigonal); Cleavage: None (Conchoidal fracture); Specific gravity: 2.58 - 2.91
Formation & geological history
Formed via silica-rich fluids permeating through porous volcanic or sedimentary rocks, often enriched with iron minerals during late-stage hydrothermal activity. This specimen shows signs of alluvial smoothing, likely tumbled in a riverbed or shoreline for thousands of years.
Uses & applications
Primarily used in jewelry (cabs, beads, pendants), lapidary art, and ornamental carvings. Historically used to make scrapers and arrowheads due to its conchoidal fracturing and hardness.
Geological facts
In antiquity, Red Jasper was known as the 'stone of endurance' and was a popular stone for creating scarabs in Ancient Egypt. The red color is caused specifically by inclusions of hematite.
Field identification & locations
Identify in the field by its high hardness (it will scratch glass) and lack of transparency (unlike agate, jasper is opaque). It is commonly found globally, particularly in areas with ancient volcanic activity like the American Southwest, South Africa, and Brazil.
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