sedimentary
Chert Nodule
Microcrystalline Quartz (SiO2)
Hardness: 6.5-7 Mohs; Color: Brown and white; Luster: Waxy to dull; Structure: Cryptocrystalline; Fracture: Conchoidal; Specific Gravity: 2.65
- Hardness
- 6
- Color
- Brown and white
- Luster
- Waxy to dull
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Physical properties
Hardness: 6.5-7 Mohs; Color: Brown and white; Luster: Waxy to dull; Structure: Cryptocrystalline; Fracture: Conchoidal; Specific Gravity: 2.65
Formation & geological history
Formed through the replacement of limestone or carbonate sediment by silica-rich fluids. Often occurs as nodules or beds within sedimentary rock layers like limestone or chalk.
Uses & applications
Historically used for stone tools (arrowheads). Today used for landscaping, as a road mineral, or for decorative lapidary work in its more colorful forms (Jasper/Agate).
Geological facts
Chert has been used by humans for millions of years because its conchoidal fracture creates sharp edges perfect for cutting and scraping tools.
Field identification & locations
Identify in the field by its waxy texture, its ability to scratch glass, and the seashell-like curves (conchoidal fracture) when broken. Commonly found in stream beds or eroded limestone outcrops.
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Chert Breccia
Brecciated Chert (Microcrystalline Silica)
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