sedimentary

Chert Pebble (Jasper/Quartz variety)

Microcrystalline Quartz (SiO2)

Hardness: 7 on Mohs scale; Color: Cream, white, and tan with dark mineral inclusions; Luster: Dull to waxy; Crystal Structure: Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.6 – 2.7.

Hardness: 7 on Mohs scale
Color: Cream, white, and tan with dark mineral inclusions
Luster: Dull to waxy

Identified March 14, 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 environments. This specimen has been significantly water-worn and smoothed, likely in a riverbed or coastal environment, over millions of years.

Uses & applications

Used historically for stone tools and weapons due to its sharp conchoidal fracture. Modern uses include decorative gravel, landscaping, and lapidary work (polishing) for hobbyists.

Geological facts

Chert is so hard that it can scratch steel. It is chemically identical to flint, though usually lighter in color. The dark spots visible are likely dendritic manganese or iron oxide inclusions trapped within the silica matrix.

Field identification & locations

Identify by its 'waxy' texture when dry and its inability to be scratched by a stainless steel knife. Found globally in limestone formations or as river pebbles. Collectors look for unique banding or patterns.

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