December 26, 2011

Novaculite—a hard, abrasive sedimentary rock—is found in large amounts in the Ouachita Mountains of Arkansas. It is perhaps the state’s oldest mined mineral, with evidence of its use dating back to prehistoric times. Most people are familiar with its use as a blade-sharpening stone, but it has other uses. Novaculite is shown here being marketed as nail files, with each color being a different grade of abrasion.