AGGREGATE Novaculite is a very durable rock that resists abrasion and is well suited for use as road base, railroad ballast, and rip-rap. Although it works especially well, its use in these applications is avoided. The reason: novaculite is so abrasive on metal that it causes excessive wear on excavating equipment used to mine it,…

European settlers in the Ouachita region were the second people to mine the Arkansas Novaculite Formation. They valued it for a different reason. They found that novaculite could be used to sharpen metal tools and weapons. They soon began producing sharpening tools and trading them with distant partners. Arkansas “whetstones,” “oil stones,” and “sharpening stones”…

Native Americans were the first people to mine the Arkansas Novaculite Formation. They noticed its conchoidal fracture and discovered that it could be knapped – just like flint – into projectile points, scrapers, and cutting tools. They mined novaculite, used it to manufacture cutting tools and weapons, and traded the material and products over a broad area.…

The most famous locality for novaculite is where the Arkansas Novaculite Formation outcrops in the Ouachita Mountains of central Arkansas and southeastern Oklahoma. It is a Devonian to Mississippian-age rock unit that ranges from about 60 feet thick in the northern Ouachitas to about 900 feet thick in the southern Ouachitas. Outcrops of the Arkansas…

Novaculite is a dense, hard, fine-grained siliceous rock that breaks with a conchoidal fracture. It forms from sediments deposited in marine environments where organisms such as diatoms (single-celled algae that secrete a hard shell composed of silicon dioxide) are abundant in the water. When the diatoms die, their silicon dioxide shells fall to the seafloor. In…