sedimentary

Chert (varieties include Flint and Jasper)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

AI-generated identification · may be incorrect

Hardness: 7 on Mohs scale; Color: typically gray, white, orange, or brown; Luster: waxy to vitreous; Crystal Structure: Trigonal (microscopic); Cleavage: none, conchoidal fracture

Hardness: 7 on Mohs scale
Color: typically gray, white, orange, or brown
Luster: waxy to vitreous

Identified April 8, 2026More sedimentary →

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Physical properties

Hardness: 7 on Mohs scale; Color: typically gray, white, orange, or brown; Luster: waxy to vitreous; Crystal Structure: Trigonal (microscopic); Cleavage: none, conchoidal fracture

Formation & geological history

Formed through the accumulation of silica-rich organic remains (like diatoms or radiolarians) or chemical precipitation in marine or groundwater environments. It often forms as nodules or bedded layers.

Uses & applications

Historically used for stone tools and weapons. Used in modern industry as grinding media and in road construction. High-quality specimens are used for jewelry (as agate or jasper) and lapidary art.

Geological facts

Chert was one of the most important raw materials for early humans because its conchoidal fracture creates extremely sharp edges; it can also be used with steel to generate sparks for fire starting.

Field identification & locations

Identify by its waxy luster, smooth conchoidal (shell-like) fractures, and its ability to scratch glass easily. Commonly found in limestone beds or as river cobbles.