AID of Moh’s SCALE of hardness.MineralsMoh’s ScaleHardness testTalc1easily scratched with the thumb-nailGypsum2scratched by the thumb-nailCalcite/ Marbles3not scratched by thumb-nail but easily cut by knifeFluorite4can be cut by knife with greater difficulty than calciteApatite5can be cut only with difficulty by knifeOrthoclase/ Feldspar6can be cut with knife with great difficulty on thin edgesQuartz7not scratched by steel, scratches glassTopaz8 Sapphire/ Corundum9 Diamond10 Flakiness index-The flakiness index of an aggregate is the PERCENTAGE by WEIGHT of particles in it whose least dimension (thickness) is less than three-fifth of their mean dimension. The test is not applicable to SIZES smaller than 6.3 mm.Impact testTo determine toughness, Impact test is carried out.A steel hammer of 20 N is allowed to fall axially in the specimen.The blow at which the specimen breaks represents the toughness of the stone.