sedimentary
Chert (Arrowhead Artifact)
Microcrystalline or cryptocrystalline Quartz (SiO2)
Hardness: 7 (Mohs scale); Color: Brownish-tan; Luster: Waxy to vitreous; Crystal structure: Trigonal (microscopic); Cleavage: None (conchoidal fracture); Specific gravity: 2.65
- Hardness
- 7 (Mohs scale)
- Color
- Brownish-tan
- Luster
- Waxy to vitreous
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Physical properties
Hardness: 7 (Mohs scale); Color: Brownish-tan; Luster: Waxy to vitreous; Crystal structure: Trigonal (microscopic); Cleavage: None (conchoidal fracture); Specific gravity: 2.65
Formation & geological history
Formed through the accumulation of silica-rich organisms (like radiolarians or diatoms) or by chemical precipitation in marine environments. This specimen has been anthropologically modified via flintknapping, likely during the Holocene or late Pleistocene epoch.
Uses & applications
Historically used for tools and weaponry (arrowheads, knives, scrapers) due to its sharp edges; modern uses include aggregate for roads and decorative landscaping.
Geological facts
Chert and its variety, flint, were the first materials used by early humans for fire-starting and precision tool making. Because it breaks in a predictable conchoidal pattern, it was the gold standard for prehistoric technology.
Field identification & locations
Identify by its waxy texture, extreme hardness (scratches glass), and the shell-like (conchoidal) ripples on the surface. As an artifact, it is primarily found in fields or near natural water sources where indigenous populations once resided.
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