206 



Fig. 7. Steenstrupite, type III. 



Here the negative rhombohedra are predominate, especially 

 ^{0221) is very well developed, /"{0445} somewhat less. Of 

 the positive rhombohedra 3(4041) is quite well developed, while 

 o{l01l) can scarcely be found in half of the cases and is 

 alvvays very insignificant; the negative rhombohedral faces are 

 always distinctly horizontally striated by combination with vicinal 

 faces, the directions of which it was impossible to measure 

 with any decisive result. Of the other rhombohedra {O881) 

 was found once the prism never. Under this type, whose size 

 varies between 1 and 10 mm, is classed the greater part of 

 the crystals from Tutop Agdierkofla. Transitions to type II are 

 very rare. 



The steenstrupite appears almost always crystallized; the 

 crystals generally lie single, spread between the other minerals; 

 two or more can also often be found grown together without 

 any traceable regularity. Twins were not observed. On the 

 pieces from Kangerdluarsuk the steenstrupite can also exist as 

 apparently massive without regular exterior limitations. From 

 conclusions made from the weak double refraction, it is not 

 essentially different from the crystallized ; every single mass 

 consists probably of one or some few individuals. 



