291 



reproduced in fig. 6, also plates parallel to {010| as a predominant 

 form, are occasionally observed. 



Angles : 



c:m = (001) : (110) = ' 

 6:m = (010) : (110)=' 

 C:0 =(001) : (111) = " 

 m:m = (110) : (nO) = 

 o-.o =(111) : (11 1) = 

 6:0 =(010) : (111) = 

 0:m = (lll) :.(110) = 

 m:s =(110j : (101) = 

 c:s =(001) : (T01) = 



Very perfectly cleavable parallel to |001|. 



According to Haushofer ^) the corresponding ijotassium-salt crys- 

 tallises with 1 H,0, and is also 7»o/ioc/m/c, but without distinct form- 

 analogy with the ihallo-stilt here described. {a:h:c = 1,4945 : 1 : 0,9174; 



Laboratory/ for Inorganic and Physical Chemistry 

 of the university Groningen, Holland. 



1) K. Haushofer, Zeits. f. Kryst. u. Miner 6. 120 (1881). 



