95 
HISINGERITE. 
By Edward S. Simpson, D.Sc., B.E., F.C.S. 
Two hydrous silicates of ferric iron are known in nature — Non- 
tronite and Hisingerite. Of these, the former has been recorded 
from many different parts of the State including' Weston i a,* but 
the latter, which is a much less common mineral, has not previously 
been observed. In fact, Anderson’s Bibliography of Australian 
Mineralogy shows that up till 1916, at least, it had not been recorded 
from any part of the Commonwealth. 
Recently, through the courtesy of H. G. Stokes, Esq., of Wes- 
tonia, and A. Montgomery, Esq., State Mining Engineer, I have re- 
ceived specimens of hisingerite from that centre. Mr. N. S. Stuckey, 
Mine Manager, says that the chief occurence is at the 740ft. level 
of the Edna May Deeps Gold Mine along a joint plane cutting the 
quartz reef at right angles to its strike. The upper water level is at 
a depth of only 75ft. and although the main rock masses (granodior- 
ite gneiss and amphibolite) arc quite tin weathered at 740ft., distinct 
evidences of weathering are apparent along this joint plane. The 
occurrence of hisingerite considerably below the surface at a posi- 
tion of incipient weathering coincides with the occurrence of non- 
tronite prevailing throughout the Western Australian Goldfields. 
The mineral at the 740ft. level is found in small masses and 
lenses associated with vein quartz, siderite, a little pvrite, and some 
indefinite products of rock weathering, possibly including saponite. 
The creamy white siderite is found not only in small masses in con- 
tact with the hisingerite but also, to a slight extent, scattered in 
granules through il. Two other small specimens from the 676ft. 
level of the same mine show small crusts of hisingerite and siderite: 
in one case coating massive pyrrhotite, in the other coating massive 
and crystallised marcasite with quartz. It is possible, therefore, that 
the silicate is a replacement of the carbonate, dilute sulphuric acid 
from the oxidation of the sulphide serving to upset the equilibrium 
originally prevailing. No evidence is available on which to form a 
definite explanation of the origin of the hisingerite. Tentatively 1 
would suggest — 
2FeCO ;r + 0 + 2(RiO.,.3H,0) - (Fe.A-2Sif).,-2H.,0 4- 2H O) 
+ 2HCO,. 
In this reaction dilute sulphuric acid acts as a catalyst, the pre- 
cipitation taking place in an almost neutral solution. 
The mineral is typical in appearance. It is apparently amor- 
phous, f dense and structureless, with a conchoida! fracture and res- 
* E. S. SimpsQn : The Minerals of Westonfa. G.S.W.A. Bull. 71, p 243 (1917) 
T Sustschinskey s microscopic study of various specimens of hisinuerite showed that 
they wore cryptoerystalline. Zoit. Kryst. 47, 231 (1909). 
