Incorporation of Impurities in Tridymites from a Used Silica Brick

H. Schneider, K. Wohlleben and A. Majdic
Forschungsinstitut der Feuerfest-Industrie, An der Elisabethkirche 27, 5300 Bonn 1, Germany (FRG)

Summary: The incorporation of impurities in tridymites taken from a used silica brick have been studied by means of a high-resolution microprobe, X-ray fluorescence, X-ray diffractometry, and optical microscopy. The bulk impurity content of the brick changes strongly from the hot zone (4.7 wt%) to the colder part of the brick (7.6 wt%), indicating material transport along the temperature gradient. The transport medium for migration processes is probably a melt occurring in narrow veins between large tridymite crystals at high temperatures. The average impurity contents of homogeneous tridymite single crystals are 0.49 wt% in the hot zone of the brick and 0.81 wt% in the cold zone. Al2O3, TiO2, and Na2O are main impurity constituents; the tridymites do not contain significant amounts of Fe2O3 or CaO. The a parameters of tridymites decrease by about 0.26% from 4.9837 Å to 4.9709 Å from the hot zone to the cold zone of the brick and the c dimension shows a smaller decrease (0.11 %) from 8.2023 Å to 8.1933 Å.

Mineralogical Magazine; September 1980 v. 43; no. 331; p. 879-883; DOI: 10.1180/minmag.1980.043.331.10
© 1980, The Mineralogical Society
Mineralogical Society (