44 ROYAL SOCIETY OF CANADA 



111 calculating this mode the nephcline is taken as consisting of 

 Boda nepheline and kaliophyllite, in the proportions of 5 to 1, which is. 

 the composition of the nepheline of the nepheline syenite, occurring 

 further to the west, in the area of the township of Dungannon.^ One- 

 half of the water found in the analysis is considered as being present in 

 the eancrinite, the remainder being regarded as belonging in part 

 to the hornblende and as existing in part as hygroscopic water. This gives 

 eancrinite in about the proportion in which it seems to be present in the 

 thin sections of the specimens analyzed. 



The various bases not required by the other minerals and remain- 

 ing over to form the hornblende, are present in the proportions required 

 to form syntagmatite, which are the proportions in which these bases are 

 found in the Hastingsite of the Dungannon nepheline syenite. The horn- 

 blende has accordingly been calculated as syntagmatite, using the theore- 

 tical values given by Zirkel.- This accounts for the existing percentages 

 of all the constituents of the rock, with the exception of an excess of 1.20 

 per cent of alumina. 



Of the rocks hitherto described, those which bear the closest re- 

 semblance to IMonmouthite are the urtites of the Peninsula of Kola.^ 

 These, however, belong to the class of the dosalanes. 



Another variety of the rock from lot 11, con. VII I, when examined 

 under the microscope, was found to contain scapolite in addition to al- 

 bite and nepheline, together with a brown hornblende, instead of hast- 

 ingsite, and a little biotite. The scapolite, which occurs in large amount, 

 shows good prismatic cleavages and is usually quite fresh. ,It has a 

 specific gravity of 2.711, showing that it is near the meionite end of 

 the scapolite series and is accordingly rich in lime. 



III. Nepheline and All-ali Syenites of the Township of Glamorgan. 



The township of Glamorgan lies immediately to the west of Mon- 

 mouth, and the nepheline and alkali syenites which occur in it have a 

 very 'marked resemblance to those of the township of Monmouth just 

 described. They all lie in the south-eastern corner of the township, 

 and as in Monmouth, they occur intimately associated with limestones. 

 There is, however, one feature presented by the Glamorgan occurrences 

 which is of special interest, namely, the frequent occurrence in them of 

 enormously coarse grained developments of the rock in the form of 

 nepheline syenite pegmatites. 



The occurrences which protrude through the drift in the middle of 

 lot 32, con. Ill, and also further souiQi, on the north end of lot 32, 



* B. J. Harrington: loc. cit. 

 ' Lehrbuch der Pétrographie, vol. 1, p. 303. 



' W. Ramsay: Das Nephelinsyenitgebiet auf der Halbinsel Kola, Fennia, 

 15, No. 2, p. 22. 



