rUh and P&nfield — Lemsfordite, Neaquehonite^ etc. \'29 



thirteen crystals or parts of stalactites which seemed suitable 

 for measurement and these have been conveniently designated 

 in the following pages by numbers. 



No. 1. The best crystal of all was a small one about .V 111 " in 

 its greatest diameter, which was attached to one of the Larger 

 stalactites and readily separated from it leaving an angular 

 cavity, marked with regular lines which arc so often seen in 

 breaking apart two crystals which have accidentally grown 

 together. This small crystal gave distinct reflections of the 



;ial and values which can probably be relied on within half 

 a degree. The crystal is triclinic and is shown in fig. 2. The 

 observed forms have been taken as follows: c, 001, 0\ &, 010, 



; M, 1K>, 7; m, 110, /'; </, 021, 24'; p, 111,— 1 and r, 1:;2, 

 — j-5. The following measurements were chosen as funda- 

 mental. 



,h. 001^010=84° 6' 6~M, 010 ^ Tl - 64° 13' 



c^M, 001^ 110 = 96 35 m* M, IlO * 110 = 56 57 



b*d, 010^021 =39° 16' 



from which the following relations are calculated. 



a = 95° 22' 

 ?=100 15 a : 6: c = 0-5493: 1: 0-5655 



y= 92 28 



In addition to the fundamental measurements given above the 

 following were made for the identification of the pyramids. 



Calculated. 

 m ^p, 110 ^ 111 = 59° 36' 58° 56' 



p ~r, 111 a 132 = 21 17 21 41 



c *p, 001 * 111=44 1 44 59 



This crystal, which was attached at its lower end, in reality 

 showed none of the M face and only a little of m in front, but 

 on top and behind it was quite perfect except for a slight 

 rounding off of the vertical edges between 010, 110 and IlO 

 by a stalactitic surface. 



The position which we have adopted for our crystal is prob- 

 ably as good as any which could have been chosen for showing 

 the relation of the faces. On the thirteen stalactites which 

 we have examined twenty-four separate forms have been iden- 

 tified whose relations and zones can be well understood from 

 the spherical projection, fig. 3, and which are distributed as 

 follows : 



Domes. 

 rf, 021, 2-V 

 e, 021, 2-i 

 / 201, 2-1 



Pinacoids. 



Prism -. 



C, 001, 



W, 110, F 



6, 010, i-i 



M, 110, / 





h, 150, 





k, 310, i-3 





I, 170, i-1 



