1392.] Mineralogy and Petrography. 



It consists essentially of nepheline and pyroxen. 

 titaniferous garnet ), apatite, sphene and eancrini 

 allotriomorphically granular, though the pyroxen. 

 or more crystallographic faces. In the finer -rain 



occurs in large quantity. The pyroxene is zonal, 

 orless nucleus, surrounded by six or seven colored 

 extinction is high and the color some shade of g 

 occurs either as isolated grains in the nepheline n 

 grains in this mineral. Cancrinite is not present 



relationship of the iolite to nephelinite is shown 

 session of a titaniferous irarnet, but in its ehein 



In consequence of a recent expedition into the Peninsula < f Kola, 



in Northwestern Eussia, the senior- 1 of the two authors last mentioned 

 has had an opportunity to make a partial geological examination of 

 this little-known territory. He finds the greater portion of the penin- 

 sula to be underlain by gneisses, mica schists and Devonian sedimen- 

 tary beds. The mountains in the neighborhood of Lake Imandra are 

 composed largely of an eleolite syenite, consisting of an intergrowth 

 of albite and microline, eleolite, aegirine, arfvedsonite. eudialite. ainig- 

 matite and a number of other rare and some new species. The aegir- 

 ine forms long prisms whose extinction is about 4-5° and whose optical 

 angle exceeds 114°. Sometimes a nearly colorless zone surrounds a 

 dark-green kernel, but usually the prisms are dark throughout. An 

 analysis of isolated material gave : 



The arfvedsonite is rare in the normal rock, but is common in its 

 peripheral phases in prismatic grains, whose extinction is 10°30'. The 

 eudialite often possesses an idiomorphic outline bounded by OK, R 

 andooP 2 . Its double refraction is usually positive, but 

 some portions of its grains are negative and other portions isotropic. 

 'Fennia. Bull. d. la Soc. d. Geog. de Finlande,3, No. 7, p. 1. 



