抄録
An essentially regular interstratification of mica (sericite) and chlorite (sudoite) has been found from an alteration area of the Matsumine Kuroko deposit of the Hanaoka mine, Akita Prefecture. The mineral was collected from a bore hole at a depth of 290 m, corresponding to the top portion or the hanging wall of the deposit. It is associated closely with sudoite (di/trioctahedral chlorite). The b asal reflections are very close to an integral series. The average basal spacing d (001) is 24.14Å. The value of d (060) is 1.504Å. The DTA curve, having a deep endothermic peak at 600°C, and the infrared pattern are similar to those of dioctahedral chlorite. The chemical analysis leads to the following approximate formulae for the two components of the mineral:
Mica (sericite): K0.8Al2 (Si3.2Al0.8) O10 (OH) 2
Chlorite (sudoite):(Mg2Al) Al2 (Si3Al) O10 (OH) 8.
Structure factors and one-dimen sional Fourier projection confirm the interstratified dioctahedral micadi/trioctahedral chlorite structure, of which the chlorite component has dioctahedral silicate and trioctahedral hydroxide layers. Fourier transforms reveal the 10Å and 14Å components with a remarkable tendency of regular alternation. Intermixing of a small amount of expandable layer is indicated by slight deviations of 00l spacings from integral submultiples and by subtle changes of the basal reflections after ethylene glycol and glycerol treatments. Interpretation of these variations in spacing and line profile by visual inspection was attempted.
