LI-BEARING TOSUDITE FROM THE BUBSOO MINE, KOREA

Mineralogical characteristics, of Li-bearing tosudite from the Bubsoo mine, Korea was studied using X-ray diffraction analysis, chemical ana lysis and electron microscopy. Tosudite occurs as cryptocrystalline fl aky aggregates in the alteration zone of Cretaceous Juwangsan volcanoc lastic rocks in the Bubsoo mine. It coexists with microcrystalline qua rtz, dickite and interstratified mica/smectite in the inner alteration zone. XRD and chemical analyses suggest that the tosudite is an 1:1 r egular interstratification of Li-bearing donbassite and beidellite. It contains 0.44 wt.% of Li2O. Potassium is the main interlayer cation. The Li-bearing tosudite might have been formed from the hydrothermal s olution having high activities of Si and Li, but low activity of K und er relatively high temperature.