【摘要】 山东蒙阴金刚石矿区金伯利岩中的尖晶石族矿物究竟是铬铁矿还是尖晶石一直倍受争议,为了确定山东蒙阴矿区形态复杂的尖晶石族矿物种类,项目组对矿区的尖晶石族矿物进行了系统的采样,利用电子探针对50件尖晶石族矿物MgO、FeO、TiO2、Al2O3、MnO、Cr2O3进行微区化学成分分析,结果显示,山东蒙阴金刚石矿区金伯利岩中尖晶石族矿物A、B端元成分复杂,不存在单纯的铬铁矿或尖晶石矿物种,以化学分子式分类为基础得到的尖晶石族矿物种类主要有:铁镁-铬铁钛、镁铁-铬铁铝钛、铁镁-铬铝铁、镁铁-铬铝铁、铁镁-铬铁钛铝、镁铁-铬铝、铁镁-铬铝7个亚种。山东蒙阴金伯利岩中尖晶石族矿物的主要端元组分为MgAl2O4、MgCr2O4、FeCr2O4,矿物化学成分分析表明,Mg质量分数较高(7.3%~11.8%),其中Fe、Mg离子数比近于1:1,构成富镁的铬铁矿。更多还原

【Abstract】 The determination of which Spinel-group minerals occur in kimberlite from diamond mining at Mengyin, Shandong Province – chromite or spinel – has been highly controversial. In order to determine the species from the spinel-group of minerals that occur at the Mengyin mine, all of which have a complex morphology, spinel-group minerals from the mine were systematically sampled. Micro-chemical compositions of MgO, FeO, TiO2, Al2O3, MnO and Cr2O3 were analyzed by electron microprobe on 50 spinel-group minerals. The results showed that: A, B end-members of the spinel-group minerals in kimberlite from the Mengyin diamond mine have complex compositions, and there is no easily defined chromite or spinel mineral species. Based on the chemical formula, the classification of the spinel-group minerals can be divided into seven subspecies: iron magnesium-chrome iron titanium, magnesium iron-chrome iron aluminum titanium, iron magnesium-chrome aluminum iron, magnesium iron-chrome aluminum iron, iron magnesium-chrome iron titanium aluminum, magnesium iron-chrome aluminum, and magnesium iron-aluminum chrome. The major end-member compositions of the spinel-group minerals in the Mengyin kimberlite are MgAl2O4, MgCr2O4 and FeCr2O4. The chemical analysis of the composition of the spinel-group minerals showed that the Mg content is higher(MgO 7.3%–11.8%), and the ratio of Fe to Mg is close to 1∶1, indicating a magnesium-rich chromite.更多还原