43 



Cordylite has as yet only been found in the crystallized 

 state ; the crystals are always of minute size. The largest 

 individuals met with reach only 3™"* in length by 1""" in dia- 

 meter. Most of the crystals, however, do not even reach 1""" 

 in the greatest dimension. 



The crystals belong, as far as can be yet ascertained, 

 to the bipyramidal class of the hexagonal system. They are 

 bounded by a hexagonal prism, three pyramidal forms, and the 

 base. Their habit is partly prismatic (figs. 7 and 8, PL II) 

 partly pyramidal (fig. 1, PI. HI). In most cases the faces are 

 dull or show only a waxy glimmer, so that sharp reflections 

 can seldom be obtained. A few selected crystals, however, 

 have admitted of angular measurements that have given most 

 accurate and agreeing results. Thus, five independent measure- 

 ments of the angle between the base and the faces of the 

 uppermost pyramid gave the same result, viz. 46° 12'; other 

 values obtained deviate by only a few minutes. 



In order that the crystallographical relation between cor- 

 dylite and parisite may be made clear, the aforesaid pyramid 

 [2) in the figure) must be given the somewhat complicated 

 symbol 



p --= {4.0.4.15}. 



From the angular value given above, viz. 

 (4.0.4. 15): (000 1 ) = 46° 12' 

 the following axial ratio for the cordylite is calculated: 



a:c= 1 : 3,3865, 

 which comes very near to the axial ratio of the parisite, viz. 

 a:c ^ 1 : 3,3645. 



The forms observed on cordylite will, according to the 

 above axial ratio, obtain the following symbols : 



с = {OOOI}, i? = {4. 0.4. 15}, q = {10Г3], 

 r = {2023}, m = {1OÎ0}. 



