Composition of some Norwegian Minerals. 



69 



ratio between the acids and bases are as 5-28 to 11-31, which 

 is most likely as 2 to 1, although it is impossible, as in the 

 case of Euxenite, to deduce any satisfactory formula before we 

 are better acquainted with the compounds in question. 



From this analysis the mineral appears to be a new species, 

 and it has accordingly been called Tyrite.* It can be most 

 readily distinguished from the Euxenite by the following cha- 

 racters : — 



By its specific gravity much higher than that of Euxenite, and 

 by being brittle. By its behaviour when heated. By its re- 

 actions with phosphate of soda and ammonia. 



And, lastly, by its chemical composition, and the absence of 

 titanic acid. In short, though it is impossible at present to fix a 

 formula for it, it must be regarded as mainly consisting of a 

 hydrous columbate of yttria. 



III. — Yttrotitanite or Keilhauite. 



This mineral was first found by Weibye, at Buoen, an 

 island, near Arendal, and was analysed simultaneously by 

 Scheerer and Erdmann, who respectively named it yttrotitanite 

 and keilhauite — it was not crystalized although it possessed 

 two cleavages. Mr Dahl has however found it crystallized at 

 Arkeroen, in regular and distinct crystals, belonging to the 

 monoklinohedric system. Some of these weighed as much as 

 2% lbs., and from their size and rough surfaces could only be 

 measured by the hand goniometer. 



The following figures give the crystalline forms : — 



Fig. 3. 



* From Tyr, the Norwegian god of war, this mineral being discovered at 

 about the same time as the commencement of the present war. 



