74 The Ottawa Naturalist. [June 



of sodalite, nepheline and aegirine. Secondary calcite is rather 

 abundant, while some clear isotropic areas with delicate cubic 

 cleavage, are probably analcite. Some small colourless needles 

 in radiating groups are probably rosenbuschite, according to Dr. 

 Washington. A pale brownish-yellow isotropic mineral is prob- 

 ably perofskite but possibly pyrochlore. Very often compara- 

 tively large, brilliantly striated cubes of pyrite are present in this 

 coarse facies. The tinguaite dykes present no unusual features. 



It is thus evident that under these headings (I & II) we have 

 varieties of the exceedingly rare type of rock for which the name 

 Ijolite was proposed in i8gi by Ramsay and Berghell.^ At present 

 this species is known to occur at only three localities, Mt. Iliwaara 

 in Finland, Kaljokthal in the Kola Peninsula in Arctic Russia, and 

 at Magnet Grove, Arkansas, U.S. Its true nature was first sus- 

 pected by Rosenbusch and proved by Ramsay, but it remained tor 

 Dr. Washington to describe its true relations and position with 

 regard to the other associated nepheline-bearing intrusives. ^ As 

 far as can be ascertained, however, the occurrences at Ice River 

 are far more complete and satisfactory, for purposes of study, than 

 any of the localities mentioned. Felspar, which is absent from the 

 European occurrences, is abundantly present at Ice river, while 

 plagioclase, which is unknown in Arkansas, is represented by 

 albite, oligoclase and anorthoclase at the British Columbia locality. 

 The Ice river types are ot special interest from the greater propor- 

 tion of ferromagnesian minerals present than in the occurrences of 

 Kola or Magnet Cove, and are remaskable in that hornblende 

 (barkevekite) largely replaces the pyroxene of the others. They 

 are really a new variety, hornblende (barkevekite) ijolites. The 

 titanite which replaces in part at least the garnet of the others, is 

 also a marked feature. Garnet or Schorlomite, however, is also 

 present at the Ice river, and Mr. F. G. Wait has analyzed a speci- 

 men of this mineral which was handed to him by Dr. Hoffman. 



The silica contents in the specimen represented under (I) was 

 ascertained by Prof N. N. Evans, of McGill University, and this 

 vi^as as before stated 36,988, but a complete analysis was made of 



the variety (II). 



^ , _ 



^ Geol. Fdren Fothandl. Stockholm, 1891. Bd. 13, 4aft, 4 pp. 300-312. 

 ^ Bull. Geol. Soc. Am., Vol. 11, 1900, pp. 389-416. 



