Abstract

In view of the use of the Wolf Rock nosean phonolite as a type example of a more sodic phonolite, based on an analysis in 1871, the rock has been reanalyzed and reexamined. The new analysis, spectrographic data, an analysis of the sanidine, and the norm are given. The new analysis shows lower SiO 2 , Fe 2 O 3 , FeO, CaO, and Na 2 O, but considerably higher K 2 O, and the rock is now compared to phonolites from Colfax, New Mexico, and Bruex, Czechoslovakia. A mineral not hitherto recorded has been found to be present. It is rich in La, Y, and Zr and may be a member of the johnstrupite-mosandrite group.

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