抄録
In order to investigate the genesis of stevensite and “hydrated talc” experimentally, naturally occurring pectolite was treated hydrothermally with 1, 2 and 4 normal magnesium chloride solution and with basic magnesium carbonate for various Mg (in basic magnesium carbonate)/Si (in pectolite) molecular ratios ranging from 0.1 to 1.5. The products were examined by means of X-ray diffraction, thermal analysis, transmission and scanning electron microscopy and chemical analysis. As a result, it was found that pectolite alters to stevensite (Mg/Si=0.1-0.3), stevensite and serpentine (Mg/Si=0.5-1.0) and serpentine (Mg/Si=1.5) by hydrothermal treatment with basic magnesium carbonate treatment. On the other hand, it altered to “hydrated talc” and small amount of serpentine by magnesium chloride solution treatment, as reported previously (Sakamoto et al, 1975a). Some considerations were made on the mechanism of the conversion process of pectolite to these layer silicate minerals.
