Magnetic, chemical and x-ray studies of magnetites from Tamil Nadu, India

Abstract

Natural intensity, susceptibility, and Kocnigsbarger ratio w0re determined and studies of R.ayloigh loops, and high field hysteresis, and variation of susceptibility with temperature from-196~ to Curio temperature w~re made on a number of magnetite-quartzitG and pyroxene granulite sampl.-s from Tamil Nadu. Fee, Fete3, and Ties proportions were estimated and cell dim~aasions were determined. Frcm the magnetic studies it is infcrr~l that in general the samples contam predornirtantty multidomain grains. In a few cases single-domain l~artieles are detected, while in a few other samples a mixture of supcrparamagnctic partiel~ and single domain states could be inferred. Tho rdativc rmrmnmaec ratio is found to increase with coercive force. The ferromagnetic rninoral in magnotito-quartzites is pure magnetite with a little alteration to b~m~tite while in pyroxene granulit~s it is a tita~iferous magnetite with a small percentage of TiOz. It is probable that the cell dimensions are dependent on oxidation in magnetites, and on the content of TiOz in titanfferous magnetites.