安徽凤阳石英岩的铁含量与磁化率的关系

Relationship Between Iron Content and Susceptibility of Quartzite in Fengyang County,Anhui Province

利用电子探针检测安徽凤阳石英岩中的含铁矿物,测量由相同矿区的石英岩加工而成的不同粒度石英砂的Fe2O3质量分数(w(Fe2O3))与磁化率。结果表明:石英岩中有磁铁矿、黄铁矿、黑云母与白云母等多种含铁矿物。这些含铁矿物主要充填在石英颗粒孔隙中,粒度大多小于0.1 mm。而石英砂中的w(Fe2O3)普遍很低(小于0.1%),其磁化率主要受磁铁矿控制。并且不同粒度的石英砂中w(Fe2O3)与磁化率存在较大差异,当石英砂中的w(Fe2O3)大于0.01%时,由Fe2+、Fe3+磁性离子含量决定磁化率大小,两者存在强正相关关系。这也反映出了石英岩的铁含量与磁化率之间的关系。因此,磁化率可作为石英岩铁含量的替代性指标。

Electronic probe is used to detect iron-containing minerals in quartzite from Fengyang County,Anhui Province.The content of Fe2O3 and magnetic susceptibility of different grain-size quartz sands separated from quartzite of the same mine area are measured.The results indicate that the quartzite contains several kinds of iron-containing minerals such as magnetite,pyrite,biotite and muscovite.These iron minerals are mainly fillings in the pores of quartz grains,the size of which is usually less than 0.1 mm.The content of Fe2O3 in quartz sands is generally low(<0.1%) while the magnetic susceptibility of quartz sands is mainly controlled by magnetite.The content of Fe2O3 and magnetic susceptibility varies widely in different grain-size quartz sands.When the content of Fe2O3 of quartz sands is more than 0.01%,the magnetic susceptibility is determined by the contents of magnetic ion of Fe2+、Fe3+.The content of Fe2O3 and magnetic susceptibility of quartz sands are high positively related.This also reflects the correlation of iron content and magnetic susceptibility of quartzite.Therefore,the magnetic susceptibility of the quartzite could be used as an alternative index for the iron content of quartzite.