12( 



brilliant facets, which reflect simuUaneously with the forms 

 e and p. Tlie faces belonging to the pinacoid of the second 

 order, e, are always very small, of triangular form and very 

 brilliant. 



The faces belonging to the forms ^; and v are also very 

 brilliant. In general they have a fine striation parallel to their 

 common combination-edge. 



The forms ji and ç are new for neptunite. The faces of 

 the former lie with parallel combination -edges on both sides 

 of å. Consequently it has the same length of the с -axis as 

 flf, and is, besides, determined by measurements given below. 

 The form ^ belongs to the zones [TlO, 30 1] and [llO, 3^1 1], 

 by which its indices are fully determined. These new forms 

 generally have small faces. Especially those belonging to g are 

 usually very narrow. As, however, they are well developed and 

 very brilliant, they generally give accurate measurements, as 

 will be seen by the figures in the following table. 



Measured Calculated 



2^:p =. (3^]t):(3n) = 47°4' 47° 4' 



p:m = [zw] : (Tlü) = 36° 47' 36° 36' 



2) : m = (3"l 1) : (Tfo) = 79° 3' 78° 55' 



q : m = (fu) : (Гю) = 45° 32' 45° 26' 



q : m = (7"l2) : (ITo) = 65° 35' 65° 13' 



Twinning is still rarer among the neptunite crystals of the 

 second type than among those of type I. Among the rich 

 material available, which has been subject to a thorough 

 examination, only a single twin crystal has been found, and 

 this was not found until the chief investigation had been 

 finished. The two individuals which form the twin crystal 

 measure only 3 — 4™™ in length in the direction of the с -axis 

 and a little more than 1""" in thickness. The twinning has 

 taken place according to the same law as with type I, the base 

 being the composition-face. The с -axes of the two individuals 



