sedimentary

Chert (specifically Novaculite)

Microcrystalline Quartz (SiO2)

AI-generated identification · may be incorrect

Hardness: 7 (Mohs scale), Color: light green to greyish-white, Luster: waxy to dull, Structure: cryptocrystalline, Cleavage: none (conchoidal fracture), Specific Gravity: 2.65

Identified July 5, 2026More sedimentary →

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Physical properties

Hardness: 7 (Mohs scale), Color: light green to greyish-white, Luster: waxy to dull, Structure: cryptocrystalline, Cleavage: none (conchoidal fracture), Specific Gravity: 2.65

Formation & geological history

Formed through the deep-sea deposition of silica-rich organisms like radiolaria and diatoms. This specific regional variety, Novaculite, is often slightly metamorphosed, found in the Ouachita Mountains area (Northwestern AR, Eastern OK, and North LA) dating to the Devonian-Mississippian periods.

Uses & applications

Abrasives (sharpening stones known as 'Arkansas Stones'), road aggregate, and historically used by Indigenous peoples for projectile points and tools due to its sharp conchoidal fracture.

Geological facts

Novaculite is a rare, high-purity variety of chert. The word comes from the Latin 'novacula', meaning razor, referring to its ability to sharpen blades to an extremely fine edge.

Field identification & locations

Found at 33.0 N, 93.4 W (South Arkansas/North Louisiana border), this is consistent with the dispersal of Novaculite from the nearby Ouachita region. In the field, it is harder than glass, has a smooth waxy feel, and breaks with curved, shell-like surfaces.