THE RECOVERY OF POTASH FROM ALUNITE. 5 
good grade, and should increase considerably the supply of com- 
mercial alunite in sight. 
Another important deposit occurs between 4 and 7 miles north 
of Marysvale and about 3 miles from the river and the station of 
Belknap, on the Denver and Rio Grande Railroad. The alunite 
lies between two rhyolite dikes running almost due south from Twin 
Peaks (better known locally as Peak St. Louis or Iron Mountain) 
to a peak (Santa Cruz claims) just north of the dividing line between 
Sevier and Piute Counties. There is a fairly good wagon road from 
Iron Mountain to Belknap. The alunite mass between these two 
dikes is from 1,200 to 1,500 feet wide and about 4,000 yards long. 
While no measurements have actually been made, the depth of the 
deposit is probably considerable. 
These alunite deposits occur at a much lower level and are more 
readily accessible than the purer crystalline deposits southwest of 
Marysvale and should be mined and shipped very cheaply. 
THE PRODUCTION OF ALUM FROM ALUNITE. 
The main commercial use of alunite heretofore has been in the 
manufacture of potash alum. This industry was introduced into 
Europe as early as the thirteenth century and assumed considerable 
prominence at Tolfa, Italy, where extensive deposits of alunite 
occur. Alum is still produced in this region by the following process: 
The mineral is calcined at low red heat in heaps or in kilns for about 
6 hours. When the oxides of sulphur begin to escape the material 
is removed and transferred to brick bins, where it is exposed to 
the air for several weeks or months, being moistened with water 
from time to time during that period. The product is then mixed 
with water and after the insoluble material has settled the clear 
solution is decanted, evaporated, and crystallized. The reactions 
taking place on heating to 500° C. may be represented thus: 
Alunite. 
1. 
K 2 0.3A1 2 3 .4S0 3 .6H 2 0= 
Potass, aluminum Alumina. Water, 
sulphate. 
2KA1(S0 4 ) 2 + 2A1 2 3 + 6H 2 
(Potass, aluminum Water, 
sulphate. 
2KA1 (S0 4 ) 2 + 24H 2 0= 
Potash alum. 
2KA1(S0 4 ) 2 24H 2 
Another method of producing potash alum from alunite, as recom- 
mended by Guyot 1 consists in heating the mineral to 800 C.° for 
1 Sur larichesse industrielle de Palunite cone en poudre. Compt. Rend. Acad. Sci. Paris, 95 pp. 
693-694; Experiences sur la calcinations de l'alunite en poudre. Idem. p. 1001-1003. 
