SYENITE AND PORPHYRY OF NEW JERSEY 581 



larity of the nephelite porphyry of Beemerville to other nephehte 

 porphyries and sunilar rocks, because the Beemerville rock, on the 

 basis of a poor analysis, was made the type of the species sussexite. 

 This matter will be discussed below. 



CRYSTALLIZATION VARIANTS OF THE BEEMERVILLE MAGMA 



The nephelite porphyry and the leucite tinguaite described by 

 Wolff occur within the main mass of nephelite syenite. We 

 believe the first to be a dyke of some magnitude, while the second 

 is a dyke only fifteen inches wide. The leucite tinguaite, also, 

 differs from the nephelite syenite in no other way than in the 

 reversal of the ferrous-ferric relation and a change in the role of 

 sulphur (see II of Table III below) . The main mass crystallized 

 completely as orthoclase, nephelite, and aegirite. The smaller 

 mass (dyke?) of nephelite porphyry is only a textural variant of 

 the same magma, while the smallest dyke, of the same chemical 

 composition, is a mineralogical variant, having produced a certain 

 amount of leucite and little or no primary orthoclase. The s3mibols 

 of the three rocks indicate clearly that there has been no chemical 

 differentiation. They are as follows: 



Nephelite syenite, Beemerville, (I) II.7.i'.3. ] 



Nephehte porphyry, Beemerville, 11.(6)7.1.3. |> Janeirose 



Leucite tinguaite, Beemerville, 11.7(8). 1.3. J 

 They all fall in the same subrang. It may be mentioned here that 

 the subrang Beemerose was estabHshed from Eakin's analysis, 

 which does not seem to be so representative of the mass as the 

 new analysis here presented. The crystalhzation variants appear 

 to be due to differences in the rates of cooHng of the three rocks, 

 an assumption based upon the respective volumes of the masses 

 concerned. That a nephehte syenite magma is capable of producing 

 leucitic rock is a matter of great interest, and the presence of 

 nearly 12 per cent of leucite in the norm of the Beemervihe nephehte 

 syenite may be significant in this respect. The great similarity 

 of the Beemerville magma to certain tinguaites, as already men- 

 tioned, is a matter of like nature, that is, the expression of magmas 

 of similar composition in feldspathic and feldspathoid form. In 

 view of some results obtained by Morey and Bowen, on the thermal 



