Abstract
Single crystals of two plagioclases, labradorite and bytownite, were hydrothermally treated at 200°C and 15 bar with changing HCl concentration of solution (MHCl=1.0∼0.001). The reaction products were investigated by analytical scanning electron microscopy. The reaction product of the labradorite in 1.0 MHCl solution was silica and those in 0.1, 0.01 and 0.001 MHCl solutions were aluminosilicate with Si/Al=6.2, 0.38, 0.10, respectively. Those of bytownite in 1.0, 0.1, 0.01 and 0.001 MHCl solutions were aluminosilicate with Si/Al=1.7, 0.58, 0.25 and 0.11, respectively. The difference of Si/Al between reaction products of those two specimens which were treated in the same condition may be due to the difference of the microtexture in the specimens.
