Underscores “_” before and after a word or phrase indicate _italics_ in the original text. Equal signs “=” before and after a word or phrase indicate =bold= in the original text. Small capitals have been converted to SOLID capitals. Illustrations have been moved so they do not break up paragraphs. Deprecated spellings have been preserved. Typographical and punctuation errors have been silently corrected. [Illustration: _Fig. 2._—Radium Halo (lower part of field) and Thorium Halo (upper part of field) in Biotite cut across cleavage. ×100.]…
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