X-RAY EXAMINATION OF SERICITE MINERALS ASSOCIATED WITH THE KUROKO DEPOSITS

Abstract

X-ray diffraction data for the sericite minerals from the Kuroko deposits are outlined along with a method for presentation of the variation in the diffraction patterns.
The samples are obtained from the alteration zones of the typical Kuroko deposits of the Shakanai, Hanaoka (Matsumine), Kosaka, and Furutobe mines of Akita Prefecture. Diffraction analysis for the oriented aggregates has revealed that they are sericite and interstratified sericitemontmorillonite with various amounts of expandable layers. For the minerals which are interstratified with from zero to small amounts of expandable layers, the peak widths of the 10-11Å and 5Å reflections were chosen to examine the extent of the interlayering and plotted in a diagram. The result indicates a close relationship of the extents of interlayering to their modes of occurrence. Polytypes identified in the samples are 2M₁, 1M, and 1Md, the last of which is found only in the interstratified minerals.