MINERALOGICAL NOTES. 153 



The same rock occurs on the southwest side of Great 

 Misery island and sections which I have cut of it and studied 

 give the same microscopical character, except that the 

 orthoclase and plagioclase are much fresher. I have also 

 cut and studied numerous sections of this rock from Wood- 

 bury's point on the Beverly shore, previously described by 

 Dr. M. E. Wadsworth as a diallage-gabbro (Geological 

 Magazine, Decade 3, Vol. 2, No. 5, p. 208, May, 1885), 

 but in the sections 1 have made, and in others made by 

 Dr. H. Hedsolt of the School of Mines, Columbia College, 

 N. Y., I have been unable to detect any diallage. On the 

 east side of the Great Misery island and on House island 

 the elreolite-zircon-syenite cuts a massive hypersthene- 

 diallage-gabbro (strike east 30° N. to S. W.) which is 

 identical in microscopical characters with a gabbro on 

 Davis neck, Bay View, Gloucester, described by Dr. M. 

 E. Wadsworth on the same page of the Geological Maga- 

 zine. This rock mass occupies the whole eastern side of 

 Great Misery island and the west shore of House island 

 which is about one-half mile distant, where it is seen cut- 

 ting the elreolite-syenite. 



Other outcrops are seen in the diorite areas of Man- 

 chester and West Gloucester, a continuation of the strike 

 to Goose cove, Annisquam, and to Davis neck, Bay View, 

 Gloucester. The trend, E. 30° N., of the various out- 

 crops from Misery island, Salem harbor, is direct to the 

 outcrop at Davis neck, on the opposite side of Cape Ann, 

 a distance of sixteen miles. 



The microscopic structure of thin sections from Great 

 Misery island in polarized light is : — Much augite with 

 inclusions of apatite and zircons, plates of hypersthene, 

 green hornblende, diallage and large plates of well-twinned 

 plagioclase (probably labradorite, sp. gr. 2.693). Ex- 

 tinction angle on p. 7°, on m. 19°. Saussurite is devel- 



