sedimentary
Jasper
Silicon dioxide (SiO2)
Hardness: 6.5-7 (Mohs); Color: Reddish-brown, earthy tones; Luster: Dull to vitreous when polished; Crystal Structure: Microcrystalline (Trigonal); Cleavage: None (Conchoidal fracture); Specific Gravity: 2.58-2.91
- Hardness
- 6
- Color
- Reddish-brown, earthy tones
- Luster
- Dull to vitreous when polished
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Physical properties
Hardness: 6.5-7 (Mohs); Color: Reddish-brown, earthy tones; Luster: Dull to vitreous when polished; Crystal Structure: Microcrystalline (Trigonal); Cleavage: None (Conchoidal fracture); Specific Gravity: 2.58-2.91
Formation & geological history
Formed through the deposition of silica from water-bearing solution into volcanic or sedimentary cracks. Red coloration typically comes from iron oxide inclusions. It can form in various geological ages from Precambrian to recent.
Uses & applications
Used primarily for semi-precious jewelry, lapidary arts, ornamental carving, and as a collector's stone. Historically used for making tools and seals.
Geological facts
Jasper has been used as a gemstone since antiquity; it was a favorite in the ancient world, mentioned in the Bible and used extensively in Knossos, Crete.
Field identification & locations
Look for a smooth, waxy surface with opaque clarity. It will scratch glass but not as easily as pure quartz. Often found in riverbeds or coastal areas as water-worn pebbles.
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