The most common combination of faces is siiown by fig. 7, 

 PI. II. The forms are here the hexagonal prism and the lowest 

 pyramid , p. The prismatic faces are almost always dull or 

 feebly glimmering. The faces of the pyramid^, on the other 

 hand, are in most cases brilHant. On crystals of this develop- 

 ment they, however, regularly show a distinct horizontal striation, 

 due to the alternation of the forms ш and p. 



The base is comparatively seldom present on the cordylite 

 crystals. It forms a small , hexagonal plane , which is always 

 smooth and very brilliant. On such crystals on which the base 

 is developed, the pyramidal faces generally are less striated 

 than on those where the base is absent. It may be stated, as 

 a rule, that among the faces of these crystals, the base is the 

 most brilliant, while the prismatic faces have the least lustre. 

 Among the pyramidal forms, p has the most, and r the least 

 brilliant faces. Thus, the lustre gradually diminishes from the 

 base to the hexagonal prism. 



In the face-combination of the cordylite crystals the forms 

 q and r play a subordinate part. They mostly occur on the 

 comparatively rare crystals of pyramidal habit (figs. 1, 2, PI. 

 III). These faces are in general very narrow, and on account 

 of their feeble lustre they can only in exceptional cases be de- 

 termined. Often they (apparently) form a continuous rounding 

 of the edge between p and m. 



The following table contains the measurements from which 

 the different forms have been determined. 



(4.0.4.15) :(0001 



) = 46° 12' 



(4. 



0.4. 



15): 



14.0. 4.15) = 92°44' 



46° 9' 









calculated 92°24' 



46° 12' 





(ЮТЗЫООО!) =52°51' 



46° 12' 









52°29' 



46° 15' 









52°25' 



46° 12' 









52°51' 



46° 12' 









Calculated 52°30' 



Hean 46° 13' 











