118 GEOLOGICAL AND MINERALOGICAL NOTES. 



thus shown to be quite distinct from any member of elseo- 

 lite-zircon-syenite group heretofore described, inasmuch 

 as it contains hypersthene and olivine without a glassy 

 ground-mass, and it is equally distinct from the typical 

 augite-syenite of Vom Rath. We, therefore, have a dis- 

 tinct variety in this Magnolia outcrop. Sections from the 

 Lanesville outcrop opposite Young avenue contain olivine. 

 In some of the sections serpentine has developed in the 

 cleavage cracks and some of the feldspars have the micro- 

 scopical characters common to anorthoclase, extinguishing 

 by sections and in patches. This is the soda-microcline 

 of Professor Brogger (Zeitschrift fur Krystallographie,Yol. 

 xvi, page 261). One section shows multiple twinned al- 

 bite intergrows directly across the twinned microcline, giv- 

 ing it a very beautiful appearance when seen in polarized 

 light. This form is characteristic of Professor Brogger's 

 microcline-microperthite in the augite-syenite rocks of Nor- 

 way. There are also numerous irregular fragments of 

 segirine and a few small triangular patches of nepheline 

 with a ground-mass of quartz as a cement. 



At the augite-syenite outcrop in Brace's Cove, East 

 Gloucester, and by the roadside on the sand beach near the 

 Niles farm buildings, on the southwest side of Eastern 

 point, the large, almost perfect tabular feldspar crystals 

 give this rock a very striking appearance. The microscopic 

 structure of thin sections, when studied with the polarizing 

 microscope, gives the following minerals in its composition : 

 much augite, green hornblende, glaucophaue and chlorite 

 as secondary products in the decomposition of the horn- 

 blende, microliths of segirine, one characteristic crystal of 

 hypersthene, magnetite, limonite, numerous zircon and 

 apatite crystals, orthoclase, microcline-microperthite, some 

 plagioclase, and a little quartz as the ground-mass. The 

 large tabular porphyritic crystals of feldspar are micro- 



