248 



W. S. BAYLLY — SYENITES FROM NEW ENGLAND. 



The feldspar was the latest of all the components to crystallize. It ((in- 

 stitutes about 80 per centof the entire rock, and occurs almost exclusively 

 in large Carlsbad twins, with irregular outlines. In spite of the abun- 



Figuke '1. — Occurrence of Nepkeline and Sodalite in Feldspar. 

 l = Nepheline ; 2 = Sodalite. 



dance of apparent crystals in the hand-specimen, the thin section contains 

 lid grains with idiomorphic forms. All have such shapes as are permitted 

 them hy surrounding grains; so that we have in this feldspathic portion 



Figure 3. — Eleolite Syenite from Red Jli". 



Tin- slide shows a portion of a basic accumulation consisting oi' biotite, hornblende, augite (rec- 

 i tngular cleavage), sphene (stippled), and magnetite. 



of the rock an interpenetrating mass of large twinned grains, which have, 



however, a well marked extension in a single direction, and thus a 



