The Use of Scanning Electron Microscopy to Identify Zeolite Minerals

Abstract

Zeolites are hydrated aluminosilicates of alkali elements and alkaline earth elements. The primary structural element is silicon-oxygen and aluminum-oxygen tetrahedrons, which are arranged in three dimension, form the spatial lattice about frame structure. The primary method of zeolite identification is the X-ray Diffraction. An alternative method for recognizing zeolites is a scanning electron microscopy (SEM) combined with chemical analysis in the microarea (SEM-EDS). Application of this method is justified because of the zeolites reach the crystal size in the range from a few microns to several millimeters about crystal habit: needle-like, cubic-like, plate-like. The one of needle-like zeolites is natrolite and carcinogenic erionite. Plate-like zeolites are represented by stilbite, heulandite, whether most commonly occurring clinoptilolite or synthetic zeolite type Na-P1. The zeolites with the cubic-like habits include philipsite, chabazite and harmotome and a number of synthetic zeolites such as Na-X and Linde-A. The use of SEM to observe the form of zeolite crystals confirmed by diffraction studies in full allows for the phase identification of these group minerals. Chemical analyzes in microarea additionally specify the nature of ion-exchange cations and the Si/Al ratio as well thermal stability and surface activity.