Hydrothermal chemistry of silicates. Part XVII. Reactions in the system BaO–B2O3–SiO2–H2O

Abstract

A partial study of hydrothermal crystallisation at 250 and 415 °C in the system BaO–B₂O₃–SiO₂–H₂O has shown the ready formation of barium silicates, borates, and borosilicates. Of five barium silicates one could not be identified with previously synthesised silicates. Also eleven barium borates and five out of six barium borosilicates could not be identified and may be, or include, novel species. All the compounds have been characterised in various ways. Three of the borosilicates have BaO/B₂O₃∼ 1 and O/(B + Si)∼ 2 as with tectosilicates. However one of these at least appears to contain hydroxyl water and all three disobey Lowenstein's rule. Three additional phases could not be classified as silicate, borate, or borosilicate because they were grown only in mixtures of crystalline phases.