00313nam a2200109 a 450000500170000002000150001708200170003210000380004924500700008726000250015730000210018220251203091902.0  a0521344441  a553,bD, die  aDietrich, R.V., Skinner, Brian J.  aGems, granites and gravels : knowing and using rocks and minerals  aCambridgebCUPc1990  aviii, 174p, 24cm