Laserfiche WebLink
9 <br />TABLE A.4 <br />Rock Hardness/Strength Descriptors <br /> <br />Lj <br />Alphanumeric <br />Descriptor <br />Descriptor <br />Criteria <br />H1 Extremely hard Core, fragment, or exposure cannot be scratched with knife or <br />sharp pick; can only be chipped with repeated heavy hammer <br />blow. <br /> <br />H2 Very hard Cannot be scratched with knife or sharp pick. Core or <br />fra ment breaks with repeated heavy hammer blow. <br /> <br />H3 Hard Can be scratched with knife or sharp. pick with difficulty (heavy <br />pressure). Heavy hammer blow required to breakspecimen. <br /> <br />H4 Moderately hard Can be scratched with knife or sharp pick with light or <br />moderate pressure. Core or fragment breaks with moderate <br />hammer blow. <br /> <br />H5 Moderately soft Can be grooved 1116 inch (2 mm) deep by knife or sharp pick <br />with moderate or heavy pressure. Core or fragment breaks <br />with light hammer blow or heavy manual pressure. <br /> <br />H6 Soft Can be grooved or gouged easily by knife or sharp pick with <br />light pressure. Can be scratched with fingernail. Breaks with <br />light to moderate manual pressure. <br /> <br />H7 Very soft Can be readily indented, grooved or gouged with fingernail, or <br />carved with a knife. Breaks with light manual pressure. <br />q? GEI Consultants, Inc.