Ceramics-Silikáty 34, (4) 315 - 330 (1990) |
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THE MINERAL GYROLITE AND ITS STABILITY UNDER HYDROTHERMAL CONDITIONS
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Števula Ladislav 1, Harman Miroslav 2, Horváth Ivan 1,
Putyera Karol 1
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1 Institute of Inorganic Chemistry, Centre of Chemical Research, Slovak Academy of Sciences,
Dúbravská cesta, 842 36 Bratislava
2 Geological Institute of the Centre of Geological Scientific Research, Slovak Academy of Sciences,
Dúbravská cesta 814 73
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The effect of temperature under hydrothermal conditions on the stability of the natural mineral gyrolite (in association with laumontite) and synthetic gyrolite was studied. The initial materials as well as the final, products were identified, by X-ray diffractography, further characteristics were determined by thermal analysis, IR spectroscopy and electron scanning microscopy. It was found that over the temperature range of 200 to 300 °C under hydrothermal conditions, both the natural and synthetic gyrolite behave analogously. At 200 °C and under pressure of saturated water vapour, gyrolite and laumonite can coexist in natural specimens owing to similar CaO/SiO₂ ratios. Above this temperature (at about 220 °C and higher) the laumontite remains stable whereas gyrolite decomposes, producing the stable hydrates truscottite and xonotlite. |
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