Abstract
Two interstratified mica/vermiculite (products A and B) derived from phlogopite were studied using both the analytical electron microscope (AEM) with ultra thin window (UTW) type EDS and X-ray diffractometer. Product A which was synthesized in 20 ml HCl solution at 120°C is R1-type interstratified mica/vermiculite containing 65-75 % mica while product B was formed in 100 ml HCl solution at 50°C is a regular 1: 1 interstratified mica/vermiculite based on evaluation of X-ray diffraction results.
In product A, the positive charge of the tetrahedral ions is lower than that of phlogopite (i.e. high Al/Si ratio) and the positive charge of the octahedral ions becomes higher as the Al content increase in the octahedral sites. In general, the chemical heterogeneity among particles in product A was not remarkable.
In product B, each positive charge of the interlayer, octahedral and tetrahedral sites are widely distributed among particles. Some particles in product B have lower positive charge of the octahedral sheet and higher positive charge of the interlayer as compared to product A and the others in product B. This result agrees with the condition of formation of Mg-rich interstratified mica/vermiculite and vermiculite which are generally formed at low temperature such as in the weathering zone and tend to have low positive charge of the octahedral sheet and high positive charge of the interlayer due to the action of supergene solution. The distribution of positive charge for other particles in product B is similar to that of product A. However, the increase of octahedral positive charge in product B is due to not the increase of Al content in the octahedral sites which was found in product A but the increase of Ti content in the octahedral sites.
