Abstract:Pyrope in kimberlites is an important indicator mineral in search for diamond,Electron microprobe analyses of garnet from kimberlites in Shandong and Liaoning were used to calculate its end member percentage and other chemical parameters by means of molecular number partitioning (Table 1). The transmittance dispersion values of garnet were determined by MPV-1 type microphotometer, and the color indices were calculated by equivalent ordinate method with equalenergy light source S_E as illumination means (Table 3). In this way, the colors of garnet have been described quantitatively. Aocording to classification by Dawson and Stephens (1975), our studied samples are mainly chrome--pyrope (DG 9), and subordinately knorringite-uvarovite-pyrope (DG 12), uvarovite-pyrope(DG 11) and low-calcium chrome-pyrope (DG 10), with small amounts of titanium pyrope (DG 1) and magnesian almandine(DG 5).A discriminant diagram showing relationship between garnet and diamond was drawn with Cr, Mg and Ca as components (Fig. 7), and this diagram can be divided into five areas (A, B, C, D and E). Pyrope falling into Area A has the closest relationship with diamond. The typomorphic characteristics of such pyrope are as follows.1. Chrome-pyrope(DG 9), low-calcium chrome-pyrope(DG 10) and uvarovite-pyrope(DG 11) are dominant.2. Chemically, it is relatively high in Cr and low in Ca(generally Cr2O3=5.73-16.41% and CaO=3.22-6.38%),belonging to pyrope which contains fairly high uvarovite and knorringite members(Table 2).3. Its color is mainly purple and red with various hues and, next, bluish green and yellowish green (Table 3).4. Its refraction indices increase with increasing Cr2O3 content, and pyrope with N 1.765-1.779 is most closely related to diamond.5. Genetically, it might have been mainly derived from xenoliths of dunite-harzburgite and websterite.