In regards to being similar to Mt Isa, the structure does look alike and the polymetalic mix is close as well, but the grades... oh boy the grades are no where what Mt Isa was when first found.
Snippet from The Queensland Mining Journal Vol 25 No. 289 from June 14 1924, page 202:
The lead carbonate ores on the surface when free from the gossan often assay over 70 per cent of lead but specimens picked up on the surface have assayed as much as 60 per cent of lead without showing, except by weight, any indication of the presence of lead at all, their appearance suggesting a composition made up of bands of greyish, yellowish, reddish, or brownish sedimentary rock. In the deeper workings - or in the surface workings at the base of some of the hills - the carbonates are mixed with finely-grained galena, carrying from 17 to 70 oz of silver to the ton and free from copper, zinc, iron, arsenic, and antimony.
One has to remember at the time they were all after lead and the copper workings, which generally are under the lead/zinc orebodies, didn't get worked until the second world war when the company was asked (forced) to by the federal government and they promptly stopped again at the end of the war.
Slightly off-topic, those old mining journals are all online at the DNRM and are quite interesting to read.
Expand
(20min delay)
