sedimentary
Chert (Arrowhead/Tool variety)
Microcrystalline Quartz (SiO2)
Hardness: 7 on Mohs scale; Color: Grayish-white with brown cortex; Luster: Waxy to dull; Crystal structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific gravity: 2.65.
- Hardness
- 7 on Mohs scale
- Color
- Grayish-white with brown cortex
- Luster
- Waxy to dull
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Physical properties
Hardness: 7 on Mohs scale; Color: Grayish-white with brown cortex; Luster: Waxy to dull; Crystal structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific gravity: 2.65.
Formation & geological history
Formed as nodules or beds in limestone or chalk through the accumulation of silica-rich organic remains (like radiolarians or diatoms) or chemical precipitation. This specific piece shows evidence of anthropogenic knapping (manual shaping).
Uses & applications
Historically used for stone tools and weaponry due to its predictable conchoidal fracture. Modernly used in jewelry (as jasper/agate), construction aggregate, and as a flint for fire-starting.
Geological facts
This specimen appears to be an anthropogenic artifact, possibly a preform or a scraper. Chert has been one of the most vital materials for human survival for over 2 million years. It creates sparks when struck against steel, leading to the name 'flint'.
Field identification & locations
Identify by its waxy texture and shell-like (conchoidal) fracture patterns. Look for 'flake scars' which indicate it was worked by human hands. Found globally, especially in areas with ancient limestone deposits.
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