24 Kraus and Cook — Datolite from Westfield, Mass. 



commonly 



QJ122} is frequently present, — often as a dull face giving no 

 reflection. 



bj223}, sometimes quite large, is among the 

 observed forms. 



MJ122}, ^123}, and a; 

 quently observed. The 

 noted first by Whitlock, 



124: 



are also among the forms fre- 



forms e'\14:8\ and /Jl-4'iof, 



were observed on several crystals. 



new 



ix \ 1-410 } gave very good readings, but e'1148} was identified 

 by zonal relationship. The location of these forms is shown 



in figure 2. n z \ 1-1*10 } is also new to the species. This form 

 may be considered well established, as shown by the following 

 angles : 



Observed. Calculated. 



m : n z = (110) : (1-1-10) 76° 49' 76° 52' 



Type two (fig. 4) also possesses a pyramidal habitus. It is 

 distinguished from type one chiefly by the absence of the basal 

 and clino-pinacoids. This type was observed seven times, pos- 

 sessing the following forms : 



a{100(, ce{102}, m x {0ll\ f g{0!2\, m{\10}, o{120}, ^{111}, 

 b{223(, e{112(, A) 113}, fi{lU\ vjlll}. 



The pinacoid a\100\ occurs as a small triangular face giving 

 excellent reflections. As in type one, the hemi-orthodome 

 a? { 102} is the predominating form. The prisms m\ 110}, and 

 o { 120} are always present though generally small, — <?jl20} 

 beveling the edge between the faces p(111) and m x (0ll). Of 

 the pyramids, ej 112} and XJ113} present large, uneven faces. 

 bj223} is usually dull. The other pyramids appear as very 

 small faces. 



Type three (fig. 5) was observed on four crystals. It may 

 be characterized as possessing a prismatic habitus. All forms 

 are well developed, — the following being noted : 



e{001}, x {102}, |{102}, m x {0\l}, g\0\2\, 



ajlOO}, 61010 



t\0\3 



m 



110}, rajlll}, i/jlll}, e|I12j, A] 113}, fji{lU 



The pinacoid $J100} is the predominating form, the others 

 being quite equally developed. All faces except the positive 



