ELECTRON-BEAM BASED IMAGING OF KIMBERLITES…PUSHING THE LIMITS

摘要

Rapid mineralogical identification via Energy Dispersive Spectrometer (EDS) equipped Scanning Electron Microscopes (SEM's) have mostly been used to image fairly coarse-grained, texturally and mineralogically simple ore types comprising common silicates and sulphide minerals, such as Pt, Au and certain Cu-bearing ores. These instruments have, however, not been extensively utilised in the imaging of more texturally complex rocks such as kimberlites, where the volumetrically significant, fine-grained alteration minerals and the large range of minerals types (and compositions) expected, can pose some challenges to the instrument and operator. Kimberlites also pose other challenges in that imaging of the valuable commodity is virtually impossible due to the very low concentration and particulate nature of diamonds, making liberation analysis rather difficult. The geological complexity and variability between, and even within facies, is another obstacle to the system in that imaging of large volumes of material is necessary in order for the system to be useful for this unique ore type.