CERUSSITE CRYSTALS FROM BROKEN HILL AND MULDIVA. 



295 



it is too large for measurement on the reflecting goniometer, 

 I, which is elongated parallel to b, being 9 cm. long by 5 cm. 

 in depth, but approximate measurements with a contact 

 goniometer leaves little doubt as to the relations of the 

 three segments. In Fig. 6 I is represented as lying on the 

 b pinacoid, but in all other similar figures in this paper the 

 crystals are placed with the vertical axis perpendicular to 

 the plane of the paper as this is the best position for show- 

 ing the orientation. On I is a small arrow-head twin the 

 exact relation of which to the larger segments could not 

 be determined; a little plumose galena is crystallised on 

 the cerussite. 



Group II (Plate III, fig. 1, Text Fig. 2).— This and 

 the succeeding three groups from the Proprietary Mine 

 are off a large specimen consisting of crystals elongated 

 parallel to the vertical axis, and measuring to about 7 by 

 1 cm.; the matrix is stalactitic limonite and short tapering 

 crystals of smithsonite are attached to the cerussite. The 

 group consists of four segments twinned in pairs on r, the 

 forms present being b (010), m (110), r (130), x (012), k (011), 

 i (021), v (031), y (102), p (111). The faces in the prism 

 zone are strongly striated vertically, but the terminal faces 



i8o°b 

 rrflo'o 75*0*14 



Fi< 



