BY C. A. SUSSMILCH AND H. I. JENSEN. 175 



It frequeDtly forms the nucleus of an amphibole group. Possibly 

 it is eudialyte. Quartz is an abundant interstitial constituent in 

 allotriomorphic grains. 

 Order of consolidation : 



1. Eudialyte(?) 



2. Arfvedsonite 



3. Felspar ■ 



4. ^girine-Augite 



5. Quartz 



Name : Orthophyric Arfvedsonite-Comendite. 

 Magmatic name ; Kallerudose (Analysis vii., p. 191). 



No.X.625. Soda-Trachyte. Loc: Portion 92, Parish Towac. 



Handspecimen : bluish-grey compact rock. 



Texture : hypocrystalline with trachytic fabric. 



Composition : the phenocrysts consist of soda-sanidine. The 

 base consists essentially of felspar microlites. In addition, the 

 rock contains small amounts of SQgirite, wohlerite, riebeckite, 

 magnetite, primary haematite, and isotropic residuum. A little 

 secondary haematite and magnetite are also present. 



Name : Wohlerite-bearing Soda-Trachyte. 



No.X.635. Soda-Trachyte. Loc: Portion 92, Parish Towac. 



Microscopic Texture : porphyritic, hiatal, perpatic. Hyalo- 

 pilitic to trachytic base, which varies in grain-size, from crypto- 

 crystalline (or hypocrystalline) to microcrystalline. 



Composition : felspar is the main constituent. Magnetite, 

 laavenite and glass are present in minor amount. The felspar 

 phenocrysts are composed of cryptoperthite. That of the base 

 consists of sanidine laths. In many parts of the base we get 

 minute needles of laaveniteC?), with nearly straight extinction, 

 and parting parallel to the prism-zone. They are optically 

 negative, and have the pleochroism a^light wine-yellow, b = 

 greenish-yellow, c= brownish -yellow, and absorption c^b>il. 

 The magnetite is rounded by corrosion. The glass is interstitial. 

 Nepheline is suspected in the base. 



Name : Hypocrystalline, Laavenite-bearing Soda-Trachyte. 



