Carbon Ownby P D, Yang X, Liu J Journal of the American Ceramic Society 75 (1992) 1876-1883 Calculated X-ray diffraction data for diamond polytypes Note: hexagonal, 2H structure known as lonsdaleite Note: theoretically calculated structure values _database_code_amcsd 0014066 2.5221 2.5221 4.1186 90 90 120 P6_3/mmc atom x y z C 1/3 2/3 .06250