sedimentary
Chert (Jasper/Flint variety)
Microcrystalline Quartz (SiO2)
Hardness: 6.5-7 on Mohs scale. Color: Brownish-tan to reddish-orange. Luster: Waxy to dull. Crystal Structure: Hexagonal (cryptocrystalline). Cleavage: None, exhibits conchoidal (shell-like) fracture. Specific Gravity: 2.65.
- Hardness
- 6
- Color
- Brownish-tan to reddish-orange
- Luster
- Waxy to dull
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Physical properties
Hardness: 6.5-7 on Mohs scale. Color: Brownish-tan to reddish-orange. Luster: Waxy to dull. Crystal Structure: Hexagonal (cryptocrystalline). Cleavage: None, exhibits conchoidal (shell-like) fracture. Specific Gravity: 2.65.
Formation & geological history
Formed through the accumulation of silica-rich organic remains or chemical precipitation in sedimentary basins. Often found as nodules in limestone or chalk beds, dating from various geological periods from Precambrian to Cenozoic.
Uses & applications
Historically used for stone tools and weapons due to sharp edges; currently used for decorative stone, lapidary jewelry, and as a component in construction aggregate.
Geological facts
Chert was one of the most important raw materials for early humans; its ability to fracture predictably into razor-sharp edges made it ideal for arrowheads and scrapers. Flint is a specific dark variety of chert.
Field identification & locations
Identify in the field by its distinctive waxy texture and curved, sharp-edged fractures. Commonly found in riverbeds, glacial tills, and outcrops of limestone. Collectors look for unique banding or internal patterns.
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