sedimentary
Chert (flint), brown variety
Microcrystalline quartz (SiO₂)
AI-generated identification · may be incorrectHardness about 7 Mohs; opaque brown to gray with a waxy or dull luster and no visible crystals. It breaks with a curved, conchoidal fracture and sharp edges; specific gravity is about 2.6.
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Physical properties
Hardness about 7 Mohs; opaque brown to gray with a waxy or dull luster and no visible crystals. It breaks with a curved, conchoidal fracture and sharp edges; specific gravity is about 2.6.
Formation & geological history
Forms when silica accumulates and replaces material in sedimentary settings, commonly as nodules in limestone or chalk. Chert occurs in rocks of many geological ages.
Uses & applications
Used historically for tools and fire-starting; today it is collected and sometimes used for decorative objects or knapped crafts.
Geological facts
Its sharp conchoidal fracture made flint valuable for prehistoric blades and projectile points.
Field identification & locations
Look for hardness near 7, a smooth curved fracture, and a waxy appearance; the specimen’s brown color and fracture fit chert, though identification from an image is uncertain. Chert is widespread worldwide, especially in sedimentary formations.
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