Substance Hardness Talc 1 Amber , Fingernail, Ivory , Shell, Jet 2.5 Gold 2-3 Bronze , Coral , Pearl 3 Iron 4 Glass 5 Opal 5.5-6.5 Amethyst , Chalcedony , Quartz , Steel (pocket knife) 7 Spinel , Topaz 8 Ruby , Sapphire 9 Diamond 10 MOHS SCALE The Mohs Scale of Hardness measures a substance's hardness, that is, how resistant it is to being scratched.
(The Mohs Scale of Hardness; measures; a substance's hardness)
The Mohs Scale of Hardness
measures
a substance's hardness