Shen Zhongyue1, Ye Ying1, L? Guanglie2, Zhou Huaiyang3, Ding Weiwei1
1. Department of Earth Science, Zhejiang University, Hangzhou, 310027; 2. Analysing and Testing Center of Zhejiang Unviersity, Hangzhou, 310028; 3. The 2nd Inst. of Oceanography, State Oceanic Bureau, Hangzhou 310012
CaCO3(Ⅱ)is found in the surface sediment of South China Sea,at longitude 117°00′,north latitude 12°00′.With its chemical composition the same as calcite,aragonite and vaterite,they all are polymorgh of CaCO3.As a natural mineral,the space group of CaCO3(Ⅱ) is found to be P2.1/c,with a lattice parameter of a0=0.6290±0.0002 nm, b0= 0.4934 ±0.0002 nm, c0=0.7979±0.0003 nm, β =107.571°±0.002°, Z =4.Volume of unit cell is 0.23605±0.1749 nm3;theoretical calculated density 2.82 g/cm3,measured density 2.76g/cm3,and measured hardness H =4.The natural CaCO3(Ⅱ)is a biological mineral being a component of a coral body formed under deep water environment with a relatively high hydrostatic pressure.