sedimentary
Jasper
Silicon dioxide (SiO2)
Hardness: 6.5-7 Mohs; Color: Brown, red, and yellowish tones (wet look); Luster: Vitreous to waxy; Structure: Microcrystalline quartz; Cleavage: None (conchoidal fracture); Specific Gravity: 2.58-2.91.
- Hardness
- 6
- Color
- Brown, red, and yellowish tones (wet look)
- Luster
- Vitreous to waxy
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Physical properties
Hardness: 6.5-7 Mohs; Color: Brown, red, and yellowish tones (wet look); Luster: Vitreous to waxy; Structure: Microcrystalline quartz; Cleavage: None (conchoidal fracture); Specific Gravity: 2.58-2.91.
Formation & geological history
Formed through the accumulation of silica from either volcanic ash or water circulation through sedimentary beds, often during the Proterozoic or Paleozoic eras. The iron oxides provide the brownish-red pigment.
Uses & applications
Used primarily as decorative gemstones, in jewelry making, for lapidary work (cabs and tumbled stones), and as historical ornamental stone in architecture.
Geological facts
The word jasper comes from the Greek word 'iaspis', meaning spotted stone. It is a dense, opaque variety of chalcedony that can contain up to 20% foreign materials which dictate its color and pattern.
Field identification & locations
Identify in the field by its hardness (cannot be scratched by steel), opaque nature even on thin edges, and smooth, waxy feel when wet or worn. Frequently found in riverbeds and gravel pits.
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