0. C. Farnngton — Azurite from Arizona. 



301 



two latter being produced by the predominance of the clino- 

 domes and orthodomes respectively. 



Pyramidal Habit.— Figs. 2, 3 and 4. This habit, which is 

 characterized by the predominance of the pyramid h, 221, 

 was found to prevail in by far the larger number of the 



specimens examined. The crystals vary much in size, are 

 usually attached by the basal plane, and the faces c, A, ra, 

 and <r, are always prominent. Each of these can usually 

 be recognized at a glance, m and h by the small angle (19° 

 57') which they make with one another, c by the striations 

 commonly present parallel to the edge ca or cb / and a from 

 the angle of nearly 45° which it makes with the adjoining 

 faces. "Where other faces are present, fig. 3, they are 

 always so small that they could not be confounded with 

 those just mentioned. In the crystal shown in fig. 4, the 

 face a so largely predominates as to give a tabular appearance. 

 A crystal of similar shape from Porto Cabello, Venezuela, is 

 figured by Schrauf (Tafel II, fig. 23) and, as he remarks, from 

 the similarity of the angles ca and oh, the crystal at first glance 

 appears to be of a rhombohedral type with a as the basal plane. 

 Aside from the one just mentioned and a crystal from Corn- 

 wall figured by Zippe, I have found no other figures of azurite 

 where the pyramid h predominates. This habit therefore may 

 be considered peculiar to the Arizona azurites. Though a 

 large number of crystals of this habit were examined, none 

 were found suitable for accurate measurement. The edges are 

 generally sharp and the faces fairly bright, but always so 

 curved or warped as to give a long series of reflections of the 

 signal on the reflecting goniometer. 



Prismatic Habit. — Figs. 5, 6 and 7. 



The crystals shown in these figures were all from a Morenci, 

 Arizona, specimen. Some have a comparatively large size, the 

 one shown in fig. 6, being 10 mm in length. They were usually 

 attached by the orthopinacoid which varied in the amount of 

 its development, but where large, gave to the crystals an appear- 

 ance very like the upper portion of the simple cut brilliant, the 



