208 Brush and Dana — Mineral Locality at Branchville. 



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First type — 



DesC? 



b 



010 



i-i 



.9 



c 



001 







P 



m 



110 



I 



m 



9 



301 



-3-i 



ok 



e 



Oil 



U 



e 1 



u 



311 



3-3 



u 



t 



341 



4-* 



i 



• 



Second type. 



DesCl. 



a 



100 



i-i 



h l 



in 



110 



1 



m 







105 



— W 

 5 * 



o« 



a 



15 -0-8 



8 * 



<»fr 



6 



435 



—4.4. 

 — 5 3 



6 



k 



19-5-8 



i a- 1& 



8 " 6 



h 



X 



IT-9-10 



11.11 



10 9 



X 



e 



9-11-10 



l n Q 



E 



The Branchville crystals, like those from Limoges, vary in 

 color from pale violet to reddish brown and deep orange-red. 

 The habit of the crystals, however, is nearly constant and the 

 angles also so far as our measurements have gone ; they corres- 

 pond to the second type of the Limoges crystals. The crystals 

 are not easy to decipher, since they are Yerj small, united by 

 parallel grouping and as a rule present only a few planes in 

 such a way as not to exhibit the symmetry. The angles are 

 not as accurate as could be desired, although the crystals are 

 much better than those of Limoges, since DesCloizeaux gives 

 his observed angles to whole degrees in many cases and the 

 majority are stated to be approximations only. 



For the sake of greater simplicity of symbols, the position 

 of DesCloizeaux is modified somewhat in that his plane 105 

 (V) is taken as the base and the pyramid d is made the unit 

 pyramid. 



For fundamental angles the following have been assumed : 



100 ,s 001=84° 1' 

 110a 110 = 62° 21' 

 110^401=70° 54' 



whence we obtain : 



a: &: c=l-9192: 1: 0-5245; = 84° 1'. 



The observed planes with the symbols of the corresponding 

 planes so far as observed by DesCloizeaux are as follows : 



a 



100 



i-i 



c 



001 



O 



m 



110 



I 



a 



401 



4-t 



/5 



501 



5-i 



P 



223 



-t 



6 



111 



— 1 



e 



221 



2 



k 



511 



5-5 



z 



621 



6-3 



I 



841 



8-2 



DesCloizeaux. 



100 



h 1 



105 



o 5 



no 



m 



15-0-8 



a^ 



435 



6 



9-n-io 



e 



195-8 



k 



The attempt to transform the symbols of DesCloizeaux, 

 according to the usual methods, into those required by this 

 change of position meets with only partial success. Thus the 

 plane 19*5 "8 becomes by the transformation 411 while the 



