SYENITE AND PORPHYRY OF NEW JERSEY 577 



general, those of eastern Canada, are characteristically dosodic, con- 

 tain less titanium, and where it has been determined, less zirconium 

 than that of Beemerville: they are also more silicic, and some of 

 the Canadian rocks have a marked tendency to show an excess of 

 alumina. The material analyzed by Eakins is termed " the average 

 rock" by Iddings. That used for the analysis here presented was 



Fig. I. — The character of the Beemerville intrusion, as inferred from the distribu- 

 tion of rock types: (i) Shawangimk conglomerate. (2) Martinsburg shale and con- 

 tact aureole. (3) Normal nephelite syenite, with occasional nepheline-rich, and lujav- 

 ritic (marginal) facies. (4) Transition of normal nephelite syenite into darker variety 

 with biotite and titanite. (5) Nephelite porphyry, with tinguaitic and sussexitic 

 facies. (6) Leucite tinguaite. (7) Ouachitite breccia of Rutan's Hill. Diagram 

 partly idealized. Main boundaries from the Franklin Furnace folio. The probable 

 occurrence of a dyke of nephelite porphyry in the northern part of the main mass is 

 suggested by an observation of Emerson, Amer. Jour. Sci., XXIII (1882), p. 308. 



collected by Dr. Wolff and is representative of the northern third 

 and the southern extremity of the mass. The non-determination 

 of TiOa and PaOj by Eakins of course affects the figures for AI2O3. 

 As has been stated already, the Beemerville nephelite syenite 

 resembles most closely the foyaite of Magnet Cove, Arkansas. 

 An analysis of the latter rock is given in Table I for comparison 

 together with a lujavrite from Umptek, described by Hackmann. 

 The Arkansas rocks are characteristically sodi-potassic, like those 



