112 
RECORDS OF TIIE AUSTRALIAN MUSEUM. 
Mr. Gibb Maitland, Assistant Government Geologist for Queens- 
land, writes me that this and similar specimens were found in 
Number 11 Floor, Freehold South Stopes, thirty-eight feet below 
the surface of the ground. They occur in a matrix of oxide of 
iron, the latter forming a dyke, eighteen feet in width, dipping to 
the north-east, and consist of nodules of all conceivable shapes and 
sizes, surrounded by iridescent oxide of iron, manganese, and 
other auriferous clayey matter. 
Mr. Jack expressed the opinion that their origin was not organic, 
which was subsequently confirmed by the Curator of the Australian 
Museum. A superficial examination of the specimen in question 
supported this view, and determined it to be a concretion of a 
basic sulphate of iron containing alkalies. On the strength of this 
result, Mr. W. R. Hall presented to the Trustees of this Museum 
the specimen already received. It seemed to me that a more exact 
determination of the nature of the body would be of interest. 
Properties . — To the naked eye the specimen appears a compact 
mass of a dull brown colour weathered slightly on the outside to a 
yellow powder. The powdered substance itself has a yellow colour, 
and under the microscope is seen to consist of minute crystals. It 
is but very slightly soluble in water, but completely soluble on 
boiling for a short time with hydrochloric acid. Heating in a tube 
causes a liberation of acid water and the substance on cooling turns 
red. Before the blowpipe it turns black, becoming highly magnetic, 
and slightly fuses on the edges. Its specific gravity is 3 -107. 
An analysis gave the following percentage composition — 
H t} 0 = 9-96 
Fe^Og = 49*13 
Na o 0 = 4*43 
K o 0 = 3*88 
S0 3 = 33*31 
100*71 
No water was given off by heating the powdered substance to 175° C. 
for two hours. The above percentage for water was obtained by 
heating a weighed quantity to dull redness for a short time, 
noting the loss of weight, and then estimating the quantity of S0 3 
left in the residue. From these numbers and the known total 
of SO 3 in the substance the amount of water was calculated. 
By extracting twice with boiling water, 0*8% was dissolved, 
which contained a trace of chloride, probably salt. 
The specific gravity and the analysis, with the exception of the 
proportion of potash to soda, agree very closely with those given 
by Dana in “A System of Mineralogy,” p. 975, for Jarosite , but 
the insolubility in water of the Mount Morgan mineral seems to 
show that the two bodies cannot be identical. The latter body 
is, without doubt, derived from the decomposition of pyrites. 
January , 1896. 
