The hardness of stone is measured by Mohs hardness as a unit…
https://www.rockdrillingtools-china.com/wp-content/uploads/2017/07/STONE.jpg10801920sdrocktoolhttps://www.rockdrillingtools-china.com/wp-content/uploads/2017/03/LOGO-300x125.jpgsdrocktool2017-07-09 23:08:032017-07-12 17:33:50Rock Stone Classification and Stone Hardness