Mohs scale of mineral hardness testing the resilience of certain flat panel display components (such as cover glass for LCDs or encapsulation for OLEDs). The Mohs scale of mineral hardness is based on the ability of one natural sample of mineral to scratch another mineral visibly. The samples of matter used by Mohs are all different minerals. Minerals are chemically pure solids found in nature. Rocks are made up of one or more minerals. As the hardest known naturally occurring substance when the scale was designed, diamonds are at the top of the scale. The hardness of a material is measured against the scale by
Rockwell scale applied, then removed while still maintaining the minor load. The depth of penetration from the zero datum is measured from a dial, on which a harder material gives a higher number. That is, the penetration depth and hardness are inversely proportional. The chief advantage of Rockwell hardness is its ability to display hardness values directly, thus obviating tedious calculations involved in other hardness measurement techniques. The equation for Rockwell Hardness is formula_1, where d is the depth (from the zero load point), and N and s are scale factors that depend on the scale of the test being used (see