No. 2385. CRYSTALLOGRAPHW STUDY OF DATOLITE— SHANNON. 533 



Zone No. 4b. — Negative pyramid zone. 

 (001) : (110) Symbol ~y • 



Form . . 



Symbol 



2v 



N« 



110 



The zone is normal, with six forms missing and two extra. Of the 

 extra forms (227), previously reported, was confirmed by one narrow 

 and poor face while (229), here listed as new was found on two 

 crystals. Both are probably established though disturbed forms. 



Zone No. 5a. — Positive pyramid zone. 



(011): (100). Symboly- y=l. 



Form . . 



Symbol 



N, 



The zone is normal, though very incomplete. Two forms are 

 extra, both of which are new. These are regarded as well founded 

 through disturbed forms. 



Zone No. 5b. — Negative pyramid zone. 

 (011) : (TOO). Symbol -^- k ,= l. 



Form.. 



Symbol 



N 2 



100 



The zone is normal, with no forms lacking and only one extra. 

 The extra form (811) observed independently by Gorgey and Gold- 

 schmidt, Ungemach, and the present .writer, can be regarded as 

 established. 



Zone No. 6. — Negative pyramid zone. 



(013) : (100). Symbol *• ^=3. 



Form... 



Symbol 



3v 



N, 



loo 



The zone is normal, having the form (1.10.30), here listed as new 

 an extra form. 



