ELECTRON PROBE SPECTRUM ANALYSIS OF CHROMITE IN MENGYIN KIMBERLITES, SHANDONG PROVINCE

Chromite is one of the main indicator minerals in kimberlite diamond deposit. Accurate content analysis of the chemical compositions such as FeO, MgO, Cr₂O₃, Al₂O₃ and TiO₂ in chromite is the key for the naming of chromite, and significant indication for kimberlite diamond deposit prospecting as well. The electron probe spectroscopy is used to analyze the major chemical elements in chromite, and the micro-area chemical analysis of measured samples to infer the mineral name. The analysis results of 25 single mineral samples show that the contents of major chemical components are 15.666%-29.971% of FeO, 7.286%-11.477% of MgO and 56.421%-71.111% of Cr₂O₃, with minor chemical components MnO 0.012%-0.382%, Al₂O₃ 0.871%-8.993% and TiO₂ 0.074%-3.375%. The total mineral chemical composition is 99.117%-100.877%. The chemical composition of single mineral is equivalent to that of chromite. According to the mineral characteristics by artificial heavy mineral identification and positions of ion groups A and B, it can be determined that the measured sample is magnochromite.