Calcite Graf D L American Mineralogist 46 (1961) 1283-1316 Crystallographic tables for the rhombohedral carbonates Locality: synthetic _database_code_amcsd 0000098 4.9900 4.9900 17.0615 90 90 120 R-3c atom x y z Ca 0 0 0 C 0 0 .25 O .2578 0 .25