sedimentary
Chert (Jasper variation)
Microcrystalline Quartz (SiO2)
Hardness: 6.5-7 Mohs scale; Color: Reddish-brown, orange-tan, and dark grey; Luster: Dull to waxy; Crystal structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific gravity: 2.6-2.7
- Hardness
- 6
- Color
- Reddish-brown, orange-tan, and dark grey
- Luster
- Dull to waxy
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Physical properties
Hardness: 6.5-7 Mohs scale; Color: Reddish-brown, orange-tan, and dark grey; Luster: Dull to waxy; Crystal structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific gravity: 2.6-2.7
Formation & geological history
Formed through the accumulation of silica-rich fluids in sedimentary environments or by the replacement of calcium carbonate in limestone. Its age can range from Precambrian to recent, often found in nodules or bedded layers.
Uses & applications
Historically used for stone tools due to its sharp edges; currently used for lapidary work, landscaping, and as a collector's specimen.
Geological facts
Jasper is an opaque variety of chalcedony. The red and brown colors in this specimen usually come from iron inclusions. Jasper has been used as a gemstone since antiquity.
Field identification & locations
Identify in the field by its smooth, waxy feel when broken and its ability to scratch glass. It often shows conchoidal (shell-like) fractures. Found worldwide, particularly in riverbeds and gravel deposits.
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