Novaculite

Novaculite, also called Arkansas Stone, is a microcrystalline to cryptocrystalline rock type that consists of silica in the form of chert or flint.

The name novaculite is derived from the Latin word novacula, meaning a sharp knife, dagger, or razor,[2] in reference to its use in sharpening.

[4] The novaculite beds of the south-central United States were deposited in the Ouachita Geosyncline, a deep-water marine trough, during Silurian to early Mississippian time.

[1] Because novaculite is very hard and dense, it has been mined since prehistoric times, first for use as arrow and spear points, and later to make sharpening stones.

[7] The weathered upper strata of Arkansas novaculite, known as tripoli or "rotten stone", are rich in silica and have found a niche market as a performance additive or filler in the coatings, adhesives, sealants, and elastomer industries.