48 
A CONTRIBUTION TO THE “CHEMISTRY OF ALUNITE.” 
By H. Rowley, 
Assistant Mineralogist and Chemist, 
[ Bead 14 th September, 1020.*) 
The total disappearance of all forms of potash for fertilising* 
purposes from the Western Australian market during the past few 
years, and the insistent demands of fruit-growers and market gar- 
deners for supplies, have led to an investigation being made of the 
various potash-bearing minerals of this State in the Geological Sur- 
vey Laboratory of Western Australia with a view to supplying this 
need. Many of the results of this investigation have already been 
published by Dr. E. S. Simpson in an official bulletin “Sources of 
Industrial Potash in Western Australia.” 
It has been the author’s privilege to more fully investigate the 
chemical properties of alunite — a basic sulphate of potash and 
alumina — a mineral which occurs in large quantities in this State 
and gives most promise of yielding commercial supplies of potash. 
The results obtained are of sufficient importance to be set out 
in detail, both as supplying data as to the chemical properties of 
the mineral for the information of mineralogists, and as supplying 
information which, it is hoped, will regulate the practice of using 
the mineral as a source of potash for agricultural purposes. 
A complete isomorphous series of minerals is known, ranging 
from practically pure KA^.3ALO ;t .4RO :! .()lLO to practicaly pure 
Naj0.3A l. l ()..4SO,.(iILO. Commercially, any member of this series 
containing an appreciable amount of potash is known as alunite. 
Strictly, only those members of the series lying between the pure 
potash compound and the mineral containing equal molecules of 
potash and soda would be alunite, whilst an excess of soda molecules 
over potash molecules would indicate the mineral known as natro- 
alunite. 
The most important deposits of alunite in Western Australia 
are situated at Kanowna and are dealt with very fully in Bulletin 
No. 77 of the Geological Survey of W.A. The following remarks 
* By permission oi the Director of the Geological Survey of Western Australia, 
