sedimentary
Red Jasper
Silicon Dioxide with Iron Oxide impurities (SiO2)
Hardness: 6.5-7 on the Mohs scale. Color: Deep reddish-brown to brick red with thin quartz veins. Luster: Waxy to vitreous, smooth water-worn surface. Crystal structure: Trigonal (microcrystalline/cryptocrystalline quartz). Cleavage: None (conchoidal fracture). Specific gravity: 2.58-2.91.
- Hardness
- 6
- Color
- Deep reddish-brown to brick red with thin quartz veins
- Luster
- Waxy to vitreous, smooth water-worn surface
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Physical properties
Hardness: 6.5-7 on the Mohs scale. Color: Deep reddish-brown to brick red with thin quartz veins. Luster: Waxy to vitreous, smooth water-worn surface. Crystal structure: Trigonal (microcrystalline/cryptocrystalline quartz). Cleavage: None (conchoidal fracture). Specific gravity: 2.58-2.91.
Formation & geological history
Formed when silica-rich fluids permeate microcrystalline sediments or volcanic ash, incorporating high amounts of hematite (iron oxide) which gives it its characteristic red color. Commonly found in sedimentary deposits and weathered stream or beach gravels.
Uses & applications
Widely used for lapidary arts, cabochons, carvings, polished beach pebbles, beads, and decorative mineral collections. Historically used for seals and amulets.
Geological facts
The red color in jasper comes from fine inclusions of hematite. Red jasper is often found on beaches as smooth, water-tumbled pebbles, sometimes showing white quartz veinlets filling small fractures.
Field identification & locations
Identified by its opaque, smooth red surface, high hardness (cannot be scratched by a steel knife), and waxy luster when wet or tumbled. Frequently found in coastal areas, river beds, and glacial till.
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