Summary: Powellite, appearing to be of primary late-magmatic origin, has been found associated with analcime, apophyllite, and calcite in a geode in phonolite. Data are: D 4·40, ε 1·984, ω 1·971, a 5·20 Å, c 11·43 Å, CaO 27·8, MoO3 61·8 (av.), WO3 11·4 (av.).
Mineralogical Magazine; June 1962 v. 33; no. 257; p. 158-161; DOI: 10.1180/minmag.1962.033.257.09
© 1962, The Mineralogical Society
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