CALIFORNIA ACADEMY OF SCIENCES. 361 



symbol. The crystal from which Fig. 5 was drawn is about 20 

 mm. across the orthodiagonal, perfectly clear and colorless, with 

 a brilliant, nearly adamatine lustre. It is one of about forty, 

 closely aggregated together on a thin slab about the size of the 

 palin of the hand. The beauty of the specimen can easily be im- 

 agined. 



"D J 



Fig. 6, en profit, represents the very strikingly rhombic habit 

 which the crystals of Colemanite may sometimes assume. Atten- 

 tion was called to the possibility of such a development in my 

 former paper (note 1. c p. 7), and the crystals on one specimen 

 from Death Valley realize it perfectly. Very minute traces of 

 b (— P), g (o P), «(-3P 3), r (f P f), v (2 P), and h (2 P ») 

 can also be seen on these crystals, but too small to be repre- 

 sented on a drawing of the scale of Fig. 6. 



c :a = 161° 28i' 

 d : y = 161° 30' 



Fig. 7, en profit, and 7 a is from another crystal on the same 

 specimen, with the clinodome c (P oc) so small as to be hardly 

 discernible. 



Figs. 8, en face, and 8 a in horizontal projection, represent the 

 tabular habit which prevails on five of the seven specimens I 

 have studied, from Death Valley. The tables are all implanted 

 by one end, and either closely aggregated in parallel position 

 over considerable areas, or with their longer dimensions radiat- 

 ing from a common centre in the form of large, more or less 

 globular concretions (one of these was over 100 mm. in diame- 

 ter), or again the crystals may be irregularly implanted. 



The combination of W (3 P oo), U (6 P oo), s (oo - P), and 

 (3 P 3) largely developed, with small faces of h (2 P oo), 

 g (o P), d (2 P 2), o (2 P 2), y (P), and b (— P), represented en 

 face in Fig. 8, in horizontal projection in Fig. 8% is seen on 

 these tables when they are well crystallized; but often the faces 

 W, U, s, and & are run into one slightly curved surface, the 

 faces on the edge of the table become very minute or disappear 

 entirely, and one thenhas delicate rhombic tables mainly parallel 

 to W (3 P oo). 



