sedimentary
Chert (Jasper)
Microcrystalline Quartz (SiO2)
Hardness: 6.5-7 on Mohs scale; Color: Red-brown to tan; Luster: Waxy to dull; Crystal structure: Hexagonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific gravity: 2.6-2.7.
- Hardness
- 6
- Color
- Red-brown to tan
- Luster
- Waxy to dull
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Physical properties
Hardness: 6.5-7 on Mohs scale; Color: Red-brown to tan; Luster: Waxy to dull; Crystal structure: Hexagonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific gravity: 2.6-2.7.
Formation & geological history
Formed from the accumulation of silica-rich organic remains or chemical precipitation from groundwater in sedimentary environments. Frequently found in Precambrian to modern marine deposits.
Uses & applications
Used historically for stone tools due to sharp edges; currently used for lapidary work, jewelry, and as decorative stone in gardens and construction.
Geological facts
Red variants are often called Jasper. It was one of the primary materials used by early humans to make arrowheads and scrapers because of its predictable conchoidal fracturing.
Field identification & locations
Identify by its smooth waxy texture and conchoidal fracture patterns. Found in river beds, beaches, and sedimentary outcrops worldwide.
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