Magnetometric and Röntgenometric Studies of Pyrrhotite from the Kawayama Mine, Japan

Pyrrhotites (FeSx), of various compositions, collected chiefly from the Kawayama mine have been subjected to investigation. The value of saturation magnetization (σs) depending on the composition is in the range of 0 ～22 e.m.u./gr. for x=1.066～1. 142. It is deduced from a maximum value of saturation magnetization that Fe3+ ions are present mainly in the B layer and partly in the A layer of the Bertaut type structure. Natural specimens of pyrrhotite are on the basis of the magnetic susceptibility versus temperature (σ-T) relations classified into four types : 1) Type I, with no α- and γ-transformations above the room temperature and very small σ in magnetic susceptibility, 2) Type II, with well defined γ-transformations, 3) Type III, showing γ-transformation superposed on σ-T curve of Weiss type, and 4) Type IV, with σ-T curve of Weiss type. The saturation magnetization and composition range are σs. ≲1 and 1.05 ≲ x ≲ 1. 09 for Type I,1≲σs≲ 6 and 1.09 ≲ x ≲ 1.11 for Type II, 6 ≲σs ≲ 15 and 1.11 ≲ x≲ 1.13 for Type III, and σs≳ 15 and x ≳ 1.13 for Type IV respectively.
A simple relation is found between the temperature of γ-transformation and the composition, making possible to determine the composition of natural pyrrhotite belonging to the Type II.
It is clear that the central part of the related ore deposit is occupied by pyrrhotite with smaller value of σs corresponding to that of the mineral with less iron deficiency than for that of the outer part.