368 CALIFORNIA ACADEMY OF SCIENCES. 



Albite. 



Two crystals of the albite accompinying 1 the needles were 

 measured, one of which is represented in Fig. 11, PI. IV. It is 

 a delicate colorless table parallel to x> P x> , 1.25 mm. long, 

 0.75 mm. wide, and 0.25 mm. thick, twined parallel to the 

 brachypinacoid. The hemipristnatic faces are very little devel- 

 oped. The following table give3 the observed and calculated 

 angles for both of the crystals measured. Crystal No. II is the 

 one figured on PI. IV, and presents a combination of — 



Crystal No. I is a similar combination with the addition of 

 n = 2 T ob . 



