66 
MINES AT TALLANGALOOK AND BONNIE DOON. 
By E. J. Dunn, F.G.S., late Director, Geological Survey . 
The Golden Mountain Mine, Tallangalook. 
Tallangalook is about 9 miles in a direction a little east of north from 
Bonnie Doon railway station and town, and the mine is just south of the 
township site. The house of the mine manager is, .by aneroid, 2,575 feet 
above sea-level. Close to the house is the boundary between the granite 
and Silurian rocks. 
Mining operations have been carried on in altered Silurian beds at no 
great distance from the granite. In fact, it appears probable that the pre¬ 
sence of gold disseminated through the Silurian rocks is directly due to the 
intrusion of the granite. One effect of the intrusion of the granite has been 
greatly to indurate some of the beds—intensely hard rocks outcropping 
close to Woolf’s battery, J of a mile below the battery on the mine ; another 
effect has been the mineralization of certain beds, as in the case of the lower 
tunnel of this mine, where the indurated rock is thickly impregnated with 
iron pyrites, and more sparingly with arsenical pyrites. Since these 
sedimentary beds were altered by the granite, the upper portions have 
undergone further alteration due to oxidation, and the result has been the 
re-softening of the beds to depths of 100 feet and more from the surface ; 
consequently, much of this rock could be picked down in its present condition. 
The Silurian beds near the granite, as a result of the alterations, show 
abundance of secondary mica, more especially in the joints and fissures. 
Thin veins of granite material appear also to have been forced through the rock 
mass in all directions. Some granite veins up to 4 inches thick also traverse 
the sedimentary beds. In the No. 3. quarry, such a dyke dipping south¬ 
west at an angle of 25° is traceable for a considerable distance. Such dykes 
are called “ floors ” by the local miners. From the decomposed Silurian 
beds a dark-red soil results, that ranges from 2 to 4 feet thick. Quartz 
veins are rarely seen in these altered sediments, and they are not apparently 
payably auriferous where they do occur. The gold is found in a finely- 
divided condition disseminated throughout the rock mass through a thick¬ 
ness vertically of from 300 to 400 feet as proved by the workings, but to what 
depth below the workings is unknown. The lateral extension of the gold 
is also unknown, but judging from its presence at the sites worked on this 
mine, and in trial pits at some distance from the actual workings, also at 
Woolf’s mine, J of a mile east, it would appear that a very considerable bulk 
of the country rock contains fine gold in small quantities. 
From the manager’s house a gully runs easterly, and on this gully, 250 
feet below the house, is the stamp battery and patent amalgamator, the 
former driven by steam, the latter by a Pelton wheel. This gully falls 
rapidly, and a few hundred yards lower down joins the Tallangalook Creek. 
At about 400 feet below the Golden Mountain battery is Woolf's battery. 
Just above the junction of the gully and the creek there is a waterfall of 
over 100 feet in height, which marks the junction of the granite and Silurian 
beds. If work on an extensive scale were undertaken, a site on the creek 
would possess many advantages over the present site of the battery. About 
15 chains south of the manager’s house the ridge rises into a hill called 
Vinegar Hill, and much of the bulk of this hill is also said to carry a little 
fine gold. 
The occurrence of gold throughout the country rock, as in this case, is 
not common in Victoria. Something similar in character is found, and has 
been worked at Wonga, near Stawell. 
