Alteration of basaltic glasses from the Central Indian Ocean

Textural, mineralogical and compositional characteristics of basaltic glass es from the Central Indian Ocean show them to be altered to varying extents through their interaction with the seawater, resulting in the formation of palagonite. The major chemical changes are the loss of Si, Mg and Ca and a gain of Na and K whilst, Fe and Ti remained immobile. It reflects that the basaltic glasses have undergone initial to intermediate stages of palagoni tisation under low temperature oxidative alterations. Subsequent accretion of ferromanganese oxides over the glasses have halted the progress of alter ation.