390 E<i(ilcstiin — Eruptive Rocks at Cuttingsville, 17. 



Ill IV v VI VII 





I 



II 



F 



010 





Cr,0 3 



None 





BaO 



Trace 





SrO 



004 





FeS 3 



0-21 





Fe 7 S 8 



008 





Li 2 



None 





Sum 



99-64 



99-60 



Specific gravity 



2-919 



99-36 10001 100-18 99-75 100-00 



I = Essexite, type phase (andose), Cuttingsville, Vt., H. E. Merwin, 

 analyst. 

 II = Essexite (essexose), Salem Neck, Essex Co., Mass. 

 Ill = Normal essexite (andose), Mt. Johnson, Quebec. 

 IV z= Essexite (hessose), Brome Mt., Quebec. 



V = Essexite (salcmose), St. Hilaire Mt., Quebec. 

 VI = Essexite (camptonose), Tofteholmen, Norway. 

 VII = Essexite (average of 20 analyses, B. A. Daly, in "Igneous Bocks 

 and Their Origin," 1914, p. 30). 



The rock is an andose, allied to camptonose, with the 

 following norm: 



Orthoelase 7-78 Olivine 9-93 



Albite 27-25 Magnetite 4-64 



Anorthite 23-35 Ilmenite 5-47 



Nephelite 4-54 Apatite 2-48 



Diopside 1307 Water, etc -98 



99-49 



Comparison of the Cuttingsville essexite shows its 

 close similarity to the type from Essex County, Massa- 

 chusetts, and to the varieties of essexite from the Monte- 

 regian Hills, Quebec. The likeness in chemical composi- 

 tion to the essexite from Tofteholmen, Norway, is but one 

 example of a striking chemical similarity between the 

 Cuttingsville rocks and some of those of southern Nor- 

 way. 2 The table facilitates comparison with the average 

 essexite as computed by Daly from twenty analyses. 



One of the variations from the type phase apparently 

 results from the local impregnation and partial assimi- 

 lation of essexite by pulaskite. Hand specimens usually 

 show dikelets and streamers of this syenite, traversing 

 essexite. The color resulting from the combination of 

 pulaskite with essexite is lighter and the grain less uni- 

 form than in simple essexite. Idiomorphic hornblende 

 and more or less definitely bounded feldspars are some- 

 times noticeable. A characteristic feature is an abund- 

 ance of titanite. 



2 Brogger, W. O, ' ' Die Eruptivgesteine des Kristianiagebietes ' ' : Vidensk. 

 Skrifter I, No. 4, 1894; No. 7, 1895; No. 6, 1897. 



