GEOLOGICAL AND MINERALOGICAL NOTES. 89 



were analyzed by Mr. Balch and the results published in 

 the Proceedings of the Essex Institute, Vol. iv, pp. 3 to 6. 

 During the past three years, I have given much time 

 to the study of these syenites, and have collected speci- 

 mens from Fluent's Point, Peach's Point and Naugus Head 

 on the Marblehead shore, Salem Neck, Winter Island, 

 Beverly Cove, Hospital Point, Curtis' Point near Mingo 

 beach, West Beach ; West Manchester, East Wenham to 

 Essex and on Coney Island and Coney Island ledges, 

 Haste ledge, Great Misery, Chubb's Island, the Ram Isl- 

 ands, House Island and also at Manchester High Rock, 

 where it forms dykes from a few inches to several feet in 

 width. The Ram Islands are principally albite-feldspar 

 granite, with the syenite cutting the islands on the south- 

 west, as dyke masses. The trend of the whole syenite 

 rock mass is N. 60, E. to S. W., dip variable. I have 

 prepared twelve microscopic sections, which I have studied 

 in detail with a petrological microscope at the Lithological 

 laboratory of Harvard University, Prof. J. Elliott Wolffe, 

 instructor. One very interesting form of which I have four 

 sections, two from Salem Neck east of Fort Lee, and the 

 others from Beverly, contains a form called micro-peth- 

 ite. It is a microscopic intergrowth of albite and ortho- 

 clase, the orthoclase twinning and the albite intergrowino- 



o o o 



directly across the twinning planes, giving a beautiful play 

 of colors under polarized light. 



I have over one hundred specimens of sodalite, that I 

 have collected on Salem Neck east of Fort Lee and on 

 some of the islands in the harbor which is equivalent to 

 saying that it is not a rare mineral in Salem. Several 

 very interesting forms, that are quite unknown, are still 

 to be studied in order to clear up the relationship which 

 these syenites bear to the granites and diorites through 

 which they cut. One peculiar form has been called leop- 



