sedimentary
Jasper / Flint / Chert
Microcrystalline Quartz (SiO2)
Hardness: 7 on the Mohs scale. Color: Brownish-red due to iron oxide inclusions. Luster: Vitreous to dull. Crystal structure: Trigonal (microcrystalline/cryptocrystalline, crypto-fibrous chalcedony). Cleavage: None (exhibits conchoidal fracture). Specific gravity: 2.60-2.65.
- Hardness
- 7 on the Mohs scale
- Color
- Brownish-red due to iron oxide inclusions
- Luster
- Vitreous to dull
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Physical properties
Hardness: 7 on the Mohs scale. Color: Brownish-red due to iron oxide inclusions. Luster: Vitreous to dull. Crystal structure: Trigonal (microcrystalline/cryptocrystalline, crypto-fibrous chalcedony). Cleavage: None (exhibits conchoidal fracture). Specific gravity: 2.60-2.65.
Formation & geological history
Formed through the diagenesis and precipitation of silica-rich solutions in marine environments or the replacement of limestone/chalk by silica-rich fluids. Often Cretaceous or older in geological age.
Uses & applications
Historically used by ancient humans for making stone tools such as arrowheads, scrapers, and blades due to its conchoidal fracture. Also used in lapidary arts, ornamental carvings, and jewelry.
Geological facts
This specimen displays clear signs of human chipping (lithic reduction), suggesting it is a prehistoric artifact or flake tool. Jasper and flint have been utilized by hominids for hundreds of thousands of years for fire-starting and cutting implements.
Field identification & locations
Can be identified in the field by its waxy luster, conchoidal fracture (smooth, curved shell-like breakage patterns), and high hardness (scratches glass). Found globally in sedimentary rock formations, riverbeds, and glacial tills.
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