68 ROYAL SOCIETY OF CANADA 



An analysis of the blue corundum which occurs associated with this 

 rock, was made by Mr. M. F. Connor, B.Sc, with the following re- 

 sults : — 



SiO. none 



ALO3 (diff) 1)6.90 



Fe^Og+FeO 0.76 



CaO 0.46 



MgO 1.00 



H.0 0.88 



lOO.UO 



Bed Alkali Syenite. 



Associated with the white or grey variety of the alkali syenite, 

 as well as with the nepheline syenite, and passing into these some- 

 times by an abrupt, though usually by a gradual transition, are cer- 

 tain highly feldspathic rocks, often occurring as very extensive in- 

 dependent masses which are distinguished in the field mainly by 

 their reddish colouj' îiL.d the marked scarcity or entire absence of 

 quarti). They differ from the white and grey varieties in that ortho- 

 clase, microcline and microperthite (the latter confined mostly to the 

 pegmatitic phases) are quite abundant and sometimes the predominant 

 feldspai*s. Plagioclase is also very plentiful, sometimes equalling in 

 amount, if not exceeding the potash feldspars. A comparatively large 

 area representative of this variety of syenite occurs intimately associated 

 with the nepheline syenite near the York river and is referred to in the 

 first published descriptions as " a reddish biotite granite resembling 

 aplit<' in appearance.''* This rock is exposed on both sides of the York 

 river extending from the eleventh to the fifteenth concession. Nepheline 

 syenite occurs on botli sides of this bathylith, and if the outcrops of this 

 rock could be traced and found continuous would doubtless form an asso- 

 ciation closely analogous to that describerl as occurring in the township 

 of Monmouth. The rock is essentially a quartz mica syenite made up al- 

 movst wholly of orthoclase. microcline, albite, quartz, biotite, and in 

 places hornblende. The biotite is in very small and exceedingly ir- 



^Am. .Tonr. Sc. Vol. XT^Vni. 1894, p. 11. 



