422 



II. A. Miers — Quartz from N 



hkO: 100 



h + k 

 h-k 



31° 34' 



464 



31 59 



4-82 



32 26 



5-03 



32 54 



5-28 



34 3 



5-98 



34 47 



6'52 



The first four images are the best ; the angle RR was meas- 

 ured as 85° 45f '. 



This face or corrosion surface is doubtless identical with, 

 that described by vom Rath* from the same locality as a right 

 hemi-scalenohedron replacing the edge RR, and accompanied 

 by -JR = {110}, the symbol being - UPJJ- = {11.7.0} = 

 {4.7.11.18}. 



The above measurements show that the face may with 

 greater probability be referred to the form {320} =— fPf= 



{1235} for which the angle is 100 : 320 = 32° 23£', (^j = 5 ). 



The angle measured by vom Rath was 31° 13' (approximate). 

 The order of the rhombohedral axes a'dopted here is such as to 

 harmonize with the indices of previous authors who have used 

 the Millerian system in describing new faces on quartz. 



Crystal No. 2 exhibits a very unusual habit (fig. 2), being 

 terminated by three large and well-developed faces of the 

 obtuse rhombohedron — ^R — {441 } which gives it the aspect 

 of a calcite termination. This extremely rare face was ob- 

 served by vom Rath on a curious crystal from the same local- 

 ity (Zeitschr. f. Krystallographie, x, 170, Taf. vi, fig. 5). There, 

 as in the present instance, the form — \R is accompanied by 

 small planes of —\R which truncate the edges of the primary 

 rhombohedron ; but the measurements of vom Rath were 

 insufficient to establish the symbols with certainty. 



On the crystal represented in fig. 2 the faces of — \R are 

 dull and drusy as though due to a corrosion which has also 

 spread partly over the small faces of —\R; the latter are 

 otherwise smooth and reflect well ; the inclinations of — \R 

 can be measured with perfect accuracy after the faces have 

 been slightly oiled. 



Measured. Calculated. 



— R\-\R = 19° 21' 19° 22' 



— R : -IR 28 48 28 50 



Crystal No. 3. — This crystal, represented in fig. 3, is interest- 

 ing on account of two faces @ x d> 2 which are right positive 

 hemiscalenohedra lying out of the usual zone Rsu. 



* Zeitschr. f. Krystallographie, x, 172. 



