50 
Dr. Simpson suggests the following structural formula for 
al unite : — • 
K 
I 
0 0 
^ I 
0- S 
6 1 
0 
0 
0 
- 0— Al 
0— Al 
0— Al 
0— Al 
0— Al 
OH 
OH 
OH 
OH 
OH 
OH 
OH 
OH 
OH 
OH 
OH 
OH 
0 — S — 0— Al 
^1 
0 o 
1 
K 
Plate IX.— Structural formula for alunite. 
