150 Van Horn and Hunt — Bournonite Crystals. 



Contact Measurements Calculated Angles 



30' 



h 



•a 



= (203) 



:(100) 



57 



z . 



a 



= (201) 



: (100) 



28 



i. 



c 



= (214) 



: (001) 



26 



p 



• c 



= (223) 



:(001) 



40 



y 



■b 



= (023) 



: (010) 



58 



m 



: a 



= (no) 



(100) 



43 



V ■ 



a 



= (310) 



(100) 



18 



<& 



:b 



= (140) 



(010) 



15 



a . 



b 



= (230) 



: (010) 



36 



V : 



b 



= (310) 



(010) 



71 



p. 



•p 



= (223) 



: (223) 



98 



57° 



29' 



27 



36^ 



27 



50 



41 



9 



59 



n 



43 



10 



17 



22 



14 



56 



35 



24 



30 72 38 



97 42 



Crystal No. 3. — Crystal No. 3 (Utali Collection) also shows 

 a short prismatic habit similar to No. 1. A drawing of this 

 crystal is shown in Fig. 4. The forms observed were all 

 large, and well developed, especially the prisms, m and /*, .and 

 the basal pinacoid c. The 10 crystal forms present were the 

 pinacoids, a{100\ 6(010), c(001); the prisms, m(110), 2(320), 

 /(120), $(140), 17(310); the dome, o(101) ; and the pyramid, 

 w(112). The angular measurements obtained are listed below : 







Contact Measurements 



Calculated Angles 



m:m = (110) 



: (110) 



87° 





86° 20' 



I: a = (320) 



: (HO) 



31 





32 1 



/••/ = (120) 



: (120) 



57 





56 8 



f:b = (120) 



: (010) 



29 





28 4 



*;m = (140) 



: (110) 



62 





61 46 



c:o = (001) 



:(101) 



43 





43 43 



c:u — (001) 



(112) 



33 





33 15 



v :b = (310) 



(010) 



72 



30' 



72 38 



Crystals No. 1 and No. 3, in general, resemble those from 

 Neudorf in the Harz, and Nagyag in Hungary, except that 

 they are inclined to be somewhat more tabular, and that the 

 macropinacoid is less developed. Crystal No. 2 seems to be 

 of different habit than crystals from other localities in its 

 distinct prismatic development in the direction of the brachy 

 axis. The habit of all three crystals is quite different from 

 certain specimens which the writer has recently seen from 

 Cornwall, England ; Horhausen, Prussia ; and Pribram, 

 Bohemia. 



Mineralogical Laboratories 



Case School of Applied Science and 



University of Michigan 



January, 1915. 



