sedimentary

Chert (Jasper variety)

Silicon Dioxide (SiO2)

AI-generated identification · may be incorrect

Hardness: 6.5 - 7 on the Mohs scale. Color: Mottled brown, tan, and gray with waxy luster. Crystal structure: Cryptocrystalline (microscopic quartz). Cleavage: None (conchoidal fracture). Specific gravity: 2.6 - 2.7.

Hardness: 6
Color: Mottled brown, tan, and gray with waxy luster

Identified March 25, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through the accumulation of silica-rich organic remains or chemical precipitation in marine or groundwater environments. This specimen likely originates from Paleozoic or Mesozoic sedimentary beds.

Uses & applications

Historically used for stone tools (knapping). Currently used as an abrasive, in landscaping/construction, and as lapidary material for jewelry like cabochons.

Geological facts

Due to its conchoidal fracture, it breaks with sharp, curved edges similar to glass, which made it the primary material for arrowheads and scrapers for prehistoric humans.

Field identification & locations

Identify in the field by its smooth, shell-like fracture pattern and high hardness (it will scratch steel and glass). Commonly found in limestone or chalk deposits as nodules or layers.