sedimentary

Chert (and its variety Flint)

Silicon Dioxide (SiO2) - Microcrystalline or cryptocrystalline Quartz

AI-generated identification · may be incorrect

Hardness: 7 (Mohs scale); Color: Variegated, often gray, tan, brown, or black; Luster: Waxy to dull; Crystal structure: Trigonal (microscopic); Cleavage: None (exhibits conchoidal fracture); Specific gravity: 2.6 – 2.65.

Hardness: 7 (Mohs scale)
Color: Variegated, often gray, tan, brown, or black
Luster: Waxy to dull

Identified March 18, 2026More sedimentary →

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At a glance

Common name: Chert (and its variety Flint)
Scientific name: Silicon Dioxide (SiO2) - Microcrystalline or cryptocrystalline Quartz
Category: sedimentary
Identified: March 18, 2026
Method: Standard

AI Estimated Value

$1-$5 for common rough specimens; $10-$50 for particularly high-quality colorful 'Jasper' or 'Agate' variants; finished arrowheads or artifacts can range from $20 to several hundred dollars.

Not an official valuation

AI estimate for general interest only — not an appraisal. Actual value depends on condition, provenance, and market demand. Verify with a professional before buying, selling, or insuring.

This identification was generated by AI and may contain errors. Verify important details before relying on them — and never use an AI result to judge whether a specimen is safe to handle. Read the full disclaimer

Physical properties

Formation & geological history

Formed through the accumulation of silica-rich organic remains (like radiolarians or sponges) or the chemical precipitation of silica in seawater/groundwater. It often forms as nodules in limestone or chalk beds across many geological ages, from the Precambrian to present.

Uses & applications

Historically used for stone tools and weapons due to its sharp edges; used in modern industry for road surfacing, as grinding media in ball mills, and occasionally in jewelry as cabochons.

Geological facts

Flint was one of the most important minerals for early humans, used to create fire (by sparking against iron pyrites) and the first sophisticated projectile points. It is so tough that it was used as building material in flint-knapping architecture in Europe.

Field identification & locations

Identify in the field by its characteristic 'curved' shell-like (conchoidal) fracture pattern and its ability to scratch glass. It is commonly found globally, particularly in areas with limestone or chalk deposits like the Cliffs of Dover or the Midwestern USA.