Comparison Study on the Shell Mineralogy of 9 Species of Modern Bivalves Living in Yellow Sea

9 popular species of modern bivalves living in Yellow Sea were selected for their shell mineral analyses. By means of X-ray powder diffraction method, the types of minerals in the shells were discerned and their components were calculated. The result shows that aragonite or calcite is the dominant mineral in the shells. According to the component of mineral, shells were divided into three sub-type, namely, aragonite shell, calcite shell and mixed shell with component of mineral by 98% aragonite, 90% calcite, 37% aragonite and 63% calcite, respectively. Species in Veneroida, Arcida had aragonite shell. Species in Pterioida had calcite shell. And species in Mytiloida had mixed shell. This research suggests that mineral component of bivalve shell closely relates to its living pattern. Bivalves that live in the sand sediments are apt to form aragonite shell. In contrast, bivalves that live by attaching themselves on the hard bottom are apt to form calcite shell or mixed shell. Furthermore, this research also suggests that at least in some species the shell size has no significant influence on the mineral component of the shell.