44 
different from that of the Glengower deposit. The latter, like the Lillicur, 
is easily pulverized between the fingers to an impalpable powder, and in 
analysis compares favorably with similar deposits in other parts of the 
world.* 
Analyses of other Victorian deposits have given the following results :— 
— 
Cardigan. 
Talbot. 
Lillicur, 
Silica per cent. 
79-89 
87-98 
83-88 
Alumina ,, 
9-95 
1-15 
7-41 
iron Oxide ,, 
trace 
— 
— 
Lime ,, 
trace 
1-06 
1-24 
Magnesia ,, 
trace 
0-38 
0-75 
w , ... /At 100° 
a er ” ... /After ignition 
5-41 
• 4-78 
9-38 
6-23 
100-03 
99-95 
99-51 
Neglecting water, the percentages of silica are 88* * * § 85, 97*09, and 89*48, 
respectively. 
The Cardigan and Talbot analyses, kindly furnished by Mr. R. H. 
Walcott, of the Technological Museum, are by Messrs. T. S. Hart and F. M. 
Krause respectively. The Lillicur analysis, by the late Mr. Cosmo Newbery,. 
is taken from the Mineral Statistics of the Victorian Mines Department for 
1885. The Cardigan sample was from a diamond-drill bore, 600 feet from 
the surface, was rather hard, and rendered impure by clayey and carbonaceous 
matter. 
The association of common opal and various forms of siliceous sinter 
with diatomaceous earth is quite common in hot-spring districts, active and 
extinct. In the form of veins in the earth, opal has been noted at Lillicur 
in Victoria,f Cooma and Wyrallah in New South Wales, t and very likely 
other Australian localities. At Glengower the deposit is a well-defined 
stratification 15 to 18 inches thick, and is probably a precipitate from a hot 
spring—a phase of the intermittent volcanic activity of the period—aided, 
possibly, by the secretionary action of the diatoms themselves.§ 
Many similar, but as yet undiscovered, deposits probably exist beneath 
the basaltic plains of the Glengower district. 
Office of Mines, 
Melbourne, 9th July, 1900. 
* Card, G. W. and Dun, W. S., The Diatomaceous Earth Deposits of New South Wales, 
Records Geo. Surv. N. S. Wales, Vol. V., Part III., 1897, p. 128. 
t Krause, op. cit. 
t Card and Dun, op. cit. 
§ W. H. Weed, Formation of Hot Spring Deposits, 9th Ann. Rep. U.S. Geol. Survey., 
p. 619 et. seq. 
