phalen] 



NEW OCCURRENCE OF UNAKITE 



311 



apatite, and zircon, together with the alteration products, chlorite, 

 epidote, and sericite, complete the list of minerals present. 



This rock has been referred to the hypersthene-akerites, a type 

 named and described by Brogger^ as being essentially quartzose 

 augite-syenites, the feldspars comprising both orthoclase and 

 plagioclase. For convenience of comparison in the subsequent dis- 

 cussion, a table of analyses is inserted. 



It will be seen that the resemblance between analysis No. i and 

 that of Brogger's green, fine-grained akerite from Barnekjern is 

 very close, and though of little import, it is of interest that the rocks 

 agree very closely as to mineralogical content, biotite being the only 

 component lacking in the Virginia rock to make the resemblance 

 perfect. More specifically the name hypersthene-akerite should be 

 applied, instead of simply akerite, and this name is here adopted. The 

 rock is also similar to Zirkel's Plauen'sche Grund hornblende-syenite 

 and Iddings' hypersthene-andesite from Richmond Mt., Nevada, to 

 draw an illustration from a less perfectly crystallized magma. The 

 types described by Gushing^ (analysis 5), the Diana gabbro of 

 Smythe,* and the Gloucester, Mass., akerite of Washington^ are all 



^ Zeitschrift fiir Crystallo graphic xvi, p. 51- 



^ Including Ti02. 



^ Bull. Geol. Soc. Am., x, 183. 



* Ibid., VI, 271-274. 



^ Jour. Geol, vi, 796-798. 



