138 EDSON S. BASTIN 



of either of these regions, the writer believes that such occurrences, 

 as that near East Union demonstrate beyond question that pyrrhotite, 

 in very considerable percentages, may occur as an original crystalliza- 

 tion from igneous magmas, and the possibility of at least a primary 

 concentration of this sort must be recognized in the study of the 

 origin of sulphide ores, particularly those of nickel and cobalt. 



