sedimentary

Chert (Jasper variety)

Cryptocrystalline Quartz (SiO2)

AI-generated identification · may be incorrect

Hardness: 6.5-7 on Mohs scale. Color: Brown, tan, and mustard yellow. Luster: Dull to waxy. Crystal structure: Trigonal (microscopic). Cleavage: None, exhibits conchoidal (shell-like) fracture. Specific gravity: 2.65.

Hardness: 6
Color: Brown, tan, and mustard yellow
Luster: Dull to waxy

Identified May 16, 2026More sedimentary →

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Physical properties

Formation & geological history

Forms through the accumulation of silica-rich organic remains or chemical precipitation from groundwater within limestone or slate beds. This specimen likely formed in a marine environment during various geological periods.

Uses & applications

Used historically for stone tools and arrowheads due to its sharp edges; used today as decorative stones, in lapidary work (polishing), and as a landscaping material.

Geological facts

Chert is so hard it can create sparks when struck against steel. It is one of the most common materials used by prehistoric humans for tool making.

Field identification & locations

Identify by its 'flint-like' waxy texture, smooth conchoidal fractures, and inability to be scratched by a steel knife. Commonly found in riverbeds or as nodules in limestone outcrops.