sedimentary

Chert (Tan/Yellow variety)

Microcrystalline Quartz (SiO2)

AI-generated identification · may be incorrect

Hardness: 7 on Mohs scale; Color: Tan, cream, or light yellow; Luster: Waxy to dull; Crystal structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific gravity: 2.65

Hardness: 7 on Mohs scale
Color: Tan, cream, or light yellow
Luster: Waxy to dull

Identified April 11, 2026More sedimentary →

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Physical properties

Hardness: 7 on Mohs scale; Color: Tan, cream, or light yellow; Luster: Waxy to dull; Crystal structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific gravity: 2.65

Formation & geological history

Formed through the accumulation of silica-rich organic remains or chemical precipitation in marine or groundwater environments. This specimen appears water-worn, likely from a fluvial or coastal environment.

Uses & applications

Historically used for stone tools (arrowheads/scrapers) due to sharp edges; currently used for road construction aggregate and sometimes as decorative stones in landscaping.

Geological facts

Chert is so hard it can scratch steel. When struck against steel, it can produce sparks, which led to its historical use as flint in firearms and fire-starting tools.

Field identification & locations

Identify in the field by its waxy texture and characteristic curved (conchoidal) breaks. Often found as nodules within limestone or as rounded pebbles in riverbeds.