sedimentary

Chert (specifically White Chert or Flint)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

AI-generated identification · may be incorrect

Hardness: 7 (Mohs), Color: Cream, white, or light tan, Luster: Waxy to vitreous, Crystal Structure: Microcrystalline, Cleavage: None (conchoidal fracture), Specific Gravity: 2.6-2.7

Identified May 9, 2026More sedimentary →

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Physical properties

Hardness: 7 (Mohs), Color: Cream, white, or light tan, Luster: Waxy to vitreous, Crystal Structure: Microcrystalline, Cleavage: None (conchoidal fracture), Specific Gravity: 2.6-2.7

Formation & geological history

Formed through the accumulation of silica-rich organic remains (like radiolarians or diatoms) or chemical precipitation from silica-rich fluids within other sedimentary rocks like limestone. Common in Paleozoic to Mesozoic strata.

Uses & applications

Historically used for stone tools (arrowheads). Today used as a decorative stone, road surfacing, and sometimes in porcelain manufacturing or as a gemstone in the form of Jasper/Agate.

Geological facts

Chert produces sparks when struck against steel, which made it a critical survival tool for making fire throughout human history. It is one of the most durable sedimentary rocks due to its high silica content.

Field identification & locations

Identify in the field by its very smooth, waxy surface and its sharp, shell-like (conchoidal) fracture edges. It cannot be scratched by a steel knife. Commonly found in riverbeds or as nodules within limestone outcrops.