Abstract
Well ordered tridymites containing atmost 0.016% Na (0.004% Na) were prepared at 1400° C from Na2WO4-(K2WO4-) fluxes using high purity amorphous silica as starting material. No further reduction of these Na-contents was attainable by soxhlet extraction. These tridymites were treated hydrothermally at temperatures between 815 and 950° C and 200 bars H2O. The products obtained were investigated optically as well as by powder X-ray methods and were analyzed for Na-contents: the hydrothermal treatment resulted either in recrystallization of tridymite or transformation into quartz mostly depending on Na-contents. Na-contents below about 0.015% tend to favour recrystallization of tridymite within the quartz field (<870° C), Na-contents above about 0.03% tend to favour formation of quartz within the tridymite field (>870° C). This may be due to influences of Na-traces either on the kinetics or on the equilibrium temperature of tridymite-quartz transformation.
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References
Ballman, A. A., Laudise, R. A.: In: Gilman, J. J., The art and science of growing crystals, p. 237–246. New York: Wiley 1963.
Kennedy, G. C., Holser, W. T.: In: Clark, S. P., Handbook of Physical Constants. Geol. Soc. Amer., Memoir 97, 1966, p. 374–379.
Rockett, T. J.: Phase relations in the system silica, boron oxide-silica and sodium oxide boron oxide—silica, Dissertation, Ohio State University, 1963.
Langer, K.: Some major and minor constituents of geochemical reference samples as determined by photometric methods. Z. Anal. Chem. 255, 26–29 (1971).
Kalsing, H.: Sprechsaal Silikatjahrbuch, 43th ed. Coburg: Sprechsaal, Müller & Schmidt 1961/62.
Flörke, O. W., Müller-Vonmoos, M.: Displazive Tief-Hoch-Umwandlung von Tridymit. Z. Krist. 133, 193–202 (1971).
Flörke, O. W.: Transport and deposition of SiO2 with H2O under supercritical conditions. Kristall und Technik 7, 159–166 (1972).
Fenner, C. N.: The stability relations of the silica minerals. Am. J. Sci. 36, 331–384 (1913).
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Flörke, O.W., Langer, K. Hydrothermal recrystallization and transformation of tridymite. Contr. Mineral. and Petrol. 36, 221–230 (1972). https://doi.org/10.1007/BF00371433
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DOI: https://doi.org/10.1007/BF00371433