sedimentary
Chert (Jasper/Flint variant)
Microcrystalline Quartz (SiO2)
Hardness: 6.5-7 Mohs; Color: Tan, beige, and white; Luster: Waxy to dull; Crystal structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); SG: 2.6-2.7
- Hardness
- 6
- Color
- Tan, beige, and white
- Luster
- Waxy to dull
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Physical properties
Hardness: 6.5-7 Mohs; Color: Tan, beige, and white; Luster: Waxy to dull; Crystal structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); SG: 2.6-2.7
Formation & geological history
Formed through the accumulation of silica-rich organic remains or chemical precipitation in marine or groundwater environments; often found in nodules within limestone or chalk beds.
Uses & applications
Historically used for stone tools/weapons due to sharp edges; currently used for road surfacing, lapidary work, and landscaping.
Geological facts
Because it breaks with a conchoidal fracture like glass, chert was one of the most important materials for early humans to create arrowheads and scrapers.
Field identification & locations
Identify by its waxy texture and sharp, shell-like (conchoidal) breaks when chipped; widespread globally in sedimentary basins.
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