sedimentary

Chert (varieties include Flint and Jasper)

Silicon Dioxide (SiO2)

AI-generated identification · may be incorrect

Hardness: 7 (Mohs scale); Color: ranges from grey, black, and brown to reddish (jasper); Luster: vitreous to waxy; Structure: microcrystalline quartz; Fracture: conchoidal (shell-like); Specific Gravity: 2.65

Hardness: 7 (Mohs scale)
Color: ranges from grey, black, and brown to reddish (jasper)
Luster: vitreous to waxy

Identified March 16, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through the accumulation of silica-rich microfossils (like radiolarians or diatoms) or chemical precipitation from groundwater within limestone or chalk beds. Age can range from Precambrian to Holocene.

Uses & applications

Used historically for stone tools and starting fires (flint); modern uses include construction aggregate, gemstones (jasper), and as a component in glassmaking and abrasives.

Geological facts

Chert was foundational to the Stone Age; its ability to break into razor-sharp edges made it the primary material for arrowheads, scrapers, and knives for thousands of years.

Field identification & locations

Identify by its 'conchoidal' fracture—the way it breaks into smooth, curved surfaces with sharp edges. It is found globally, often as nodules in limestone or as solid bedded deposits in marine sedimentary rocks.