sedimentary
Chert / Flint Jasper
Microcrystalline Quartz (SiO2)
Hardness: 6.5-7 (Mohs scale); Color: Brown, tan, or ochre; Luster: Dull to waxy; Structure: Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.6-2.65
- Hardness
- 6
- Color
- Brown, tan, or ochre
- Luster
- Dull to waxy
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Physical properties
Hardness: 6.5-7 (Mohs scale); Color: Brown, tan, or ochre; Luster: Dull to waxy; Structure: Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.6-2.65
Formation & geological history
Formed through the accumulation of silica-rich organic remains or chemical precipitation in sedimentary basins. Commonly found in limestone or chalk beds.
Uses & applications
Historically used for making stone tools (arrowheads). Modernly used as decorative stones, in landscaping, or for lapidary work.
Geological facts
This specimen shows the characteristic blocky, opaque appearance of chert. Because of its hardness and the way it shatters into sharp edges, it was the primary material for prehistoric weapons.
Field identification & locations
Identify in the field by its hardness (cannot be scratched by steel) and smooth, shell-like fracture surfaces. Often found as nodules within sedimentary rock layers.
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