I thought I'd have another look at the Wallaby mine since MCO...

I thought I'd have another look at the Wallaby mine since MCO management were nice enough to provide a nice plan of the mine in the quarterly.

I had a look at the Gaffneys Creek goldfields History notes from heritagevic gov.au and apparantly the mine operated between 1860's - 1926. 7000 ounces were mined from less than 6dwt/ton so average grades were below 9.3g/ton.

Thanks to Chiefjoseph and the Argus reports he provided, it seems that all the exploration on the Wallaby was by adits and drives. Due to its remote location I doubt that anyone has drilled there.

The size of the dyke differs a little depending on what report you read, but I'd say that the Argus report on the 22nd Jan 1925 has it correct. It quotes in a lot of detail when excavating the lower adit the Eastern wall of the dyke was at 730ft along the total length of tunnel which was 1022ft and ended on the Western contact. That makes the width of the dyke at that level to be about 90m. The surface expression of the dyke according to the plan is a little larger so I'm assuming that the dyke was 300ft wide by 700ft or about 210m long as was quoted on another of chiefs argus reports.

The lower adit was about 140m deep so it looks like the plans that MCO have on the page are very proportional to all the information but I'm going to assume that the provided scale is wrong. MCO conservatism!

Apparantly MCO geologists have yet to verify the exact size on the surface due to Blackberry infestations and also in the lower adit, but like I said I reckon the Argus has got it right.

Its interesting to note that the A1 dyke was only 150m long by 50m wide. The Wallaby dyke in cross sectional area is more than twice as big. Both dykes are quite vertical and have irregularities along sides, so I reckon they may well be very comparable. Its interesting to note also that A1 was developed down to about 600m. It produced 450,000 ounces at 22gr/ton but during much of its history the high grade came from a select few very rich reefs like the Victory reef. I think the Wallaby will prove to be the same.

Its interesting also to play with the numbers and what wasn't mined from the Wallaby. Assuming that the average grade was 9 gr/ton and 7000 ounces mined we get about 18,000 tons through the mill. That means that about 6000 cubic metres of diluted reef material was milled.

The plan shows some drives on the plan view which follow the reefs at each level. The Western contact reef and the reefs adjacent to it seemed to get most of the attention. From one of chiefs posts formation no 5 was 5ft wide and was driven for 200ft. the only drive that long is the one on the western contact reef. Another reef which was 2 ft wide was driven for 110ft. No 3 lode was 12ft wide and driven for 50 ft.

Basically these reefs were not very thin and to get 6000 cubic metres or 18000 tons would not require much mining. The reefs are continuous and plannar in this kind of geology. If the old timers had completely mined the bird's nest and the flower of forest reefs on the Wallaby assuming average reef widths and hardly any dilution they will have more than the total mined tonnage.

It basically means that over 2/3 of the reefs in the provided plans are still intact. Furthermore nothing seems to have been touched below 140 m ie the lower adit. Its also obvious from what we know about these reefs in the dyke swarm that very high grade gold does occur in some reefs. They are there to be found by MCO drills this summer.