sedimentary

Chert (Jasper/Chalcedony mix)

Microcrystalline Quartz (SiO2)

AI-generated identification · may be incorrect

Hardness: 6.5-7 Mohs; Color: Tan, brown, white, and grey; Luster: Waxy to dull; Crystal structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific gravity: 2.6

Hardness: 6
Color: Tan, brown, white, and grey
Luster: Waxy to dull

Identified June 29, 2026More sedimentary →

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Physical properties

Hardness: 6.5-7 Mohs; Color: Tan, brown, white, and grey; Luster: Waxy to dull; Crystal structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific gravity: 2.6

Formation & geological history

Formed through the accumulation of silica-rich organic remains or chemical precipitation in sedimentary environments. Often found as nodules in limestone or replaced organic matter. This specimen shows significant weathering on the outer rind.

Uses & applications

Historical use for stone tools and arrowheads; modern use in lapidary work, landscaping, and as a decorative mineral specimen.

Geological facts

Chert was one of the first materials used by early humans to create sharp tools due to its conchoidal fracture which produces razor-sharp edges. It is often synonymous with flint.

Field identification & locations

Identify in the field by its hardness (it can scratch glass and steel) and its smooth, shell-like fracture pattern. Commonly found in riverbeds and ancient sedimentary basins.