148 GEOLOGICAL AND 



Thoulet solution, gives the following portions as deter- 

 mined by the Westphal balance : specific gravity 2.75 

 separated out the mica hornblende, augite, zircon and 

 magnetite; 2.726 removed some remaining scales of bio- 

 tite with labradorite ; 2.614, ekeolite, plagioclase and 

 albite ; 2.595, microcline and albite, which forms the 

 largest proportion of the crushed rock ; 2.585, orthoclase 

 and microcline, leaving sodalite and orthoclase as the 

 residue. 



In the same field with the type and usually associated 

 with it is a tine-grained rock in which the elgeolite is only 

 detected with the aid of the microscope and where the 

 microcline and albite intergrows are in the form of minute 

 lath-shaped crystals. Again the feldspar is principally 

 orthoclase. In such feldspar sections there is no ela^olite. 

 In some quite basic areas the feldspars are well-formed 

 crystals which have all the microscopic characters of anor- 

 thoclase. 



Associated with all of the other forms are masses and 

 streaks which are foliated and schistose having all the ap- 

 pearance of crystallized sediments. That these schistose 

 masses are remnants of original flows in the then uncon- 

 solidated magma of the eleeolite-zircon-syenite is plainly 

 evident by comparing them with certain well-known Cam- 

 brian crystalline sediments, such, for instance, as those at 

 Naugus head on the Marblehead shore, Woodbury's point 

 on the Beverly shore and the cove on the west shore of 

 Great Misery island, which are cut by masses and veins 

 of this syenite containing large inclusions and fragments 

 of these Cambrian rocks with perfect outline. By these 

 examples it will be seen at once that the former schistose 

 rocks are totally unlike the latter and could not be mis- 

 taken for them. Other causes of variation in these syen- 

 ites are due in part to the acidic or basic quality of the 



