sedimentary
Chert / Flint
Microcrystalline Quartz (SiO2)
AI-generated identification · may be incorrectHardness: 7 on Mohs scale; Color: Gray, tan, brown, or black with waxy luster; Crystal Structure: Microcrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65.
- Hardness
- 7 on Mohs scale
- Color
- Gray, tan, brown, or black with waxy luster
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Physical properties
Hardness: 7 on Mohs scale; Color: Gray, tan, brown, or black with waxy luster; Crystal Structure: Microcrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65.
Formation & geological history
Formed by the accumulation of siliceous remains of organisms or chemical precipitation from groundwater within sedimentary layers like limestone. Found in strata ranging from Precambrian to recent.
Uses & applications
Historically used for stone tools and weapons (arrowheads); used industrially in road surfacing and as a raw material for ceramics and glass.
Geological facts
Chert and flint were arguably the most important materials for early human technology because of their ability to break into razor-sharp edges through conchoidal fracturing.
Field identification & locations
Identify by its smooth, waxy luster and classic curved (shell-like) fracture surfaces. It will easily scratch glass and will not react with acid.
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