0=, 



Measured. Calculated. 



(437"l) : (7341) = 50° 10' 49° 50' 



(43У1) : (4731)--- 68° 25' 68° 22'. 



These crystals are small and attain only 2 — 3°"° in length. 

 They are of a yellowish grey or smoky brown colour. Crystals 

 of this type have been met with only at the locality No. 2. 



Crystals of the third type are generally somewhat larger 

 than the foregoing types. They reach nearly l^"" in length 

 and show the following forms (Fig. 7, Plate I): 



с = {0001}, r={l0Tl}, (ö) = {3582}, (/?) = {0885}. 



As is seen from the figure, the scalenohedron fa) and the 

 fundamental rhobohedral r predominate. The base and the ne- 

 gative rhombohedron (/9), on the contrary, occur as very small 

 faces. These faces are, however, very bright and smooth, 

 while the planes of the fundamental rhombohedron have no 

 lustre at all. As on the crystals of the first type, these faces have 

 been affected by some solvent, which has made them quite dull 

 and produced furrows parallel to the cleavages. The faces of 

 the scalenohedral form, which are the largest on these crystals, 

 are bright, but at the same time very uneven, so that the 

 results of the measurements are not quite certain. The form 

 is determined bv the following angles. 







Measured. 



Calculated. 



(3582) : 



: (3852) = 



41° 53' 

 4Г31' 



42° 45' 

 40° 21' 







Mean 41° 38' 



41° 46' 



(3582) 



: (8532)== 



72° 37' 



72° 54' 



(3582) : 



: (0001) =- 



75° 5' 



74° 47'. 



