sedimentary
Jasper (Iron-rich)
Silicon Dioxide (SiO2) with Fe2O3 (Hematite) inclusions
Hardness: 6.5-7 on Mohs scale. Color: Opaque brown, reddish-brown, and tan. Luster: Dull to waxy. Structure: Microcrystalline/Cryptocrystalline. Specific Gravity: 2.58-2.91.
- Hardness
- 6
- Color
- Opaque brown, reddish-brown, and tan
- Luster
- Dull to waxy
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Physical properties
Hardness: 6.5-7 on Mohs scale. Color: Opaque brown, reddish-brown, and tan. Luster: Dull to waxy. Structure: Microcrystalline/Cryptocrystalline. Specific Gravity: 2.58-2.91.
Formation & geological history
Formed from the deposition of silica-rich fluids in cracks or volcanic cavities, often associated with hydrothermal activity. Over time, the silica crystallizes into microcrystalline quartz, with high iron content providing the brown/red pigmentation.
Uses & applications
Commonly used in lapidary work for making cabochons, beads, and decorative carvings. Historically used for making stone tools and seal stones.
Geological facts
Jasper is an opaque variety of chalcedony. The name comes from the Greek word 'iaspis', meaning spotted stone. It is often found as smooth water-worn pebbles in riverbeds due to its extreme durability and resistance to weathering.
Field identification & locations
Look for a smooth, waxy texture when wet and a conchoidal (shell-like) fracture pattern. It is much harder than steel and cannot be scratched by a knife. Commonly found in riverbeds, deserts, and coastal areas globally.
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