sedimentary

Chert (Jasper/Agate mix)

Microcrystalline Quartz (SiO2)

AI-generated identification · may be incorrect

Hardness: 6.5-7 (Mohs); Color: Brown, tan, and reddish-brown; Luster: Waxy to vitreous (glassy); Structure: Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.6-2.7

Hardness: 6
Color: Brown, tan, and reddish-brown
Luster: Waxy to vitreous (glassy)

Identified July 19, 2026More sedimentary →

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Physical properties

Hardness: 6.5-7 (Mohs); Color: Brown, tan, and reddish-brown; Luster: Waxy to vitreous (glassy); Structure: Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.6-2.7

Formation & geological history

Commonly formed from the accumulation of silica-rich organic remains (like diatoms) or chemical precipitation from fluids in sedimentary basins. Hardened over millions of years through lithification.

Uses & applications

Tumbled for jewelry, historical use for stone tools (flint knapping) due to sharp edges, and general landscaping or collecting.

Geological facts

Chert is extremely durable and chemically stable. Ancient civilizations used similar material to create arrowheads and scrapers because it breaks into sharp, predictable edges.

Field identification & locations

Identification includes its waxy texture and inability to be scratched by a steel nail. This specific specimen shows water-worn rounding, likely from a river or stream bed.