Abstract
THE close external crystallographic similarity between potassium sulphate and potassium beryllium fluoride, K2BeF4, has previously been pointed out by Fedorov and Barker. Both salts crystallise in the orthorhombic system, and are pseudo-hexagonal. Adopting standard orientation, the respective axial elements are: For K2SO4, a: b: c = 0.7418: 1: 0.5727, and for K2BeF4, a: b: c = 0.7395: 1: 0.5708. It has further been suggested that, since the salts exhibited some structural analogies as indicated by the formulæ, this external similarity might be accompanied by true physical isomorphism. (The well-established isomorphism in the exactly analogous series NaNO3 – calcite and KBF4 – KClO4 – BaSO4 is of interest in this connexion.)
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CURJEL, W. A New Type of Alum. Nature 123, 206 (1929). https://doi.org/10.1038/123206a0
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DOI: https://doi.org/10.1038/123206a0
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