Paragenesis of minerals of ludwigite series

The paragenesis of ludwigite has been frequently described by Geijer, Watanabe, Tilley and others, however, that of paigeite has not been described in detail. The present paper purports to describe the paragenesis of paigeite from the Kamaishi mine, Iwate Pref., Japan, and to clarify the difference in the paragenesis of paigeite and ludwigite, moreover, to discuss their genesis. Assuming a similarity of temperature and pressure during the formation of paragenesis of paigeite and ludwigite, and that chemical potentials of H2O, CO2, Na2O, K2O, B2O3 in the pore fluids participating in the formation of these parageneses were alike, and further that changes in the chemical potential of Fe had no effect on the composition of diopside, forsterite, phlogopite, spinel and tourmaline, but that, they it may be had a striking effect on the composition of the mineral of ludwigite series, concluded that the paragenesis of paigeite was formed in a condition where the chemical potential of O2 in the pore fluids was low and that of Fe in the system was high, whereas, the paragenesis of ludwigite was formed in a condition where the chemical potential of O2 was high and that of Fe was low.