400 Eggleston — Eruptive Rocks at Cutting sville, Vt. 



I = Augite syenite, nordmarkite, type phase (nordmarkose), Cuttings- 

 ville, Vt., C. D. Tost, analyst. 

 II = Nordmarkite (nordmarkose), Shefford Mountain, Quebec. 



III = Hornblende-biotite nordmarkite (pklegrose), Ascutney Mountain, Vt. 



IV = Nordmarkite (laurvikose), Annerofl, Norway. 



V = Akerite (phlegrose), between Thinghoud and Fjelebua, Norway. 

 VI = Quartz nordmarkite (toscanose), Halasag, Ditro, Siebenbiirgen, 



Hungary. 

 VII — Nordmarkite (average of 7 analyses, R. A. Daly). 



II Quoted from Dresser, J. A., Amer. Geologist, vol. 2$, p. 



209, 1901. 

 Ill " " Daly, R. A., U. S. Geol. Surv., Bull. 209, p. 



59 1903 

 IV, V, VI " " Washington, H. S., U. S. Geol. Surv., Prof. 



Paper 14, pp. 171, 195, 203. 

 VII " " Daly, R. A., "Igneous Rocks and Their Ori- 



gin", p. 22. 



The rock is nordmarkose, with the following norm : 



Quartz 5-40 Hypersthene -79 



Orthoclase 28-36 Magnetite 2-32 



Albite 59-74 Ilmenite -30 



Anorthite 1-67 Water, etc -22 



Diopside 2-85 



101-65 



Hand specimens of the Cuttingsville augite syenite 

 and the Ascutney Mountain nordmarkite very closely 

 resemble each other and the Shefford Mountain nord- 

 markite. The resemblance is so close that hand speci- 

 mens of the three are practically indistinguishable. 

 Although the Cuttingsville rock contains the highest per 

 cent of silica, thin sections of the Ascutney rock seem 

 to show the most quartz, and thin sections of the Cut- 

 tingsville rock the most augite. The Shefford Mountain 

 rock, judged in this manner, appears to be intermediate 

 between the other two. 



The Cuttingsville augite syenite has a quarts-bearing 

 phase. It is apparently quite subordinate to the type 

 phase, and occupies no well-defined area. Generally it is 

 developed as a selvage, a few feet in width, along the con- 

 tact of the augite syenite and the country rocks. It is 

 usually finer-grained than the type phase, but the quartz 

 is always distinctly visible, sometimes forming a consid- 

 erable part of the rock. With diminution of the propor- 

 tion of dark silicates, the finer-grained rock becomes quite 

 ' aplitic. Some of it, of aplitic or paisanitic habit, occurs 



