Effect of Transition Elements upon the Nucleation and the Morphology of Magnetite in Silicate Melts of Basaltic Composition

Effects of transition elements, Ti, Cr and Cu upon the nucleation and morphology of mag-netite in silicate melts of basaltic compositon were examined. Crystallization of magnetite was carried out at △T= — 10°C in the atmospheric condition. Quenched products are composed of magnetite, (plagi-oclase) and silicate glass. Examinations of the morphology of magnetite show that an addition of Ti and Cu with Keff < 1, promotes the development of dendritic and/or skeletal morphologies, whereas Cr, with Keff >1, has a definite effect to decrease grain size and to increase the number of crystals. The results obtained were discussed in relation to σ*, σ** and Keff.