sedimentary
Chert / Flint
Silicon Dioxide (SiO2)
AI-generated identification · may be incorrectHardness: 7 (Mohs scale), Color: tan, grey, brown with waxy luster, Crystal structure: microcrystalline/cryptocrystalline, Fracture: Conchoidal (shell-like), Specific gravity: 2.65
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Physical properties
Hardness: 7 (Mohs scale), Color: tan, grey, brown with waxy luster, Crystal structure: microcrystalline/cryptocrystalline, Fracture: Conchoidal (shell-like), Specific gravity: 2.65
Formation & geological history
Formed through the accumulation of silica-rich organic remains (like radiolaria or diatoms) or by chemical precipitation within limestone or chalk beds. This specimen appears as a nodule typically found in Paleozoic to Mesozoic sedimentary layers.
Uses & applications
Historically used for stone tools (arrowheads, scrapers) due to sharp edges; currently used as construction aggregate, road surfacing, and decorative garden stone.
Geological facts
Flint is a variety of chert that occurs specifically in chalk or marl. When struck against steel, it can create sparks, making it essential for early fire-starting and flintlock firearms.
Field identification & locations
Identify in the field by its smooth, waxy surface contrasting with a rough exterior 'rind' and its characteristic sharp, curved fracture patterns. Commonly found in riverbeds or limestone outcrops.
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