Ann: Greater Duchess Maiden Mineral Resource, page-99

Thanks for that share of really useful information, some very informative stuff in there, and a good thumb suck attempt at comparing peer deposits in the area and also further afield.

I might be able to make some additions to your comments that may or may not be useful for other posters on this forum:



In order of your tables and comments:

1. Ernest Henry is a world-class large deposit with only 30-40m of pre-strip cover. I believe the original resource calculation of Ernest Henry (just the open pit part) was a lot smaller and the deposit has subsequently proven to be even larger and kept a very large mill fed for decades e.g. open pit maxed out and then went shaft and underground mining, still operating. Always been MIM/Xstrata/Glencore until sold to Evolution. A legitimate world-class deposit.

2. Osborne is a typical medium-sized IOCG and like Ernest Henry started out as a small pit and went underground earlier, a smaller mill was kept fed for over 25-30 years which isn't bad for an original mine life of 10-12 years. Had a scare during the late '90s metal price swoon but operated for a long time and mill topped up by extra ore from Kulthor (very close) and Trekelano (a longer road haul). I'll include Kulthor here as it was a later satellite discovery that used all the existing Osborne infrastructure so had a lower capital hurdle as Osborne was already built and producing. Owned by CSR Minerals, Placer-Dome/Barrick/Ivanhoe Australia & now Innova-> Chinova.

3. The Starra group of mines (also known as Selywn) discovered out-cropping in the 1980s and the mill was built fairly early on, has a lot of stonking high-value gold and copper ore open pits and underground called Mt Elliot, and the 215, 222, 236, 244, 251, 257, 276, 286 & 296 orebodies, but was probably "high graded" by various short term focussed owners and by the mid-2000s the mill was becoming unreliable. Look at the $/ton metal value in todays prices of the Starra Group of mines, some of these had extremely high gold grades and if discovered at today's prices and not depleted during the low Cu price 1980s and 1990s it would have been called a world-class orebody. In 2004-ish Ivanhoe Australia dismantled the mill and went back to exploration leaving them with a lot of new discoveries and low-med grade orebodies all stranded without a mill, and the whole enterprise is now owned by Chinova. Ownership history was Amoco/Arimco/Elders Resources/Cypress Minerals then Australian Resources Limited then Selywn Mines Ltd then Ivanhoe Australia then sold to Innova Resources who became Chinova.

Mt Dore and SWAN share the same ownership history and geography as the Selwyn Group of mines and were low grade and never economically compelling and/or had met issues and the weird Merli Rhenium discovery still sits there unmined (again - weird metallurgy?).

Here is the best summary of the entire Selwyn Group of mines (Geology, exploration and history of operations)

Chapter 4_DRAFT_SELWYN Region Deposits_22Nov18_300dpi_compressed.pdf (uq.edu.au)

All of these are good peers/historical examples of Eastern Fold belt Cu-Au deposits and obviously, the bits and pieces that CNB has done resources on recently are a bit smaller scale, the common story is that a lot of these things are complex, structurally repeated, vertical and can be mined at depth and some are high grade and some lower grade, but they all far exceeded their original mine lives except in cases where the metallurgy was too weird or the deposits were "stranded" too low grade/too far from an operating mill. They have all risen and fallen more with global Cu prices and the specific management and sometimes decisions about the placement of mills and trucking distances as well as the quality of the original feasibility studies, and sometimes a bit of dumb luck and/or exploration success.



Your other examples are maybe less relevant and more WA-centric but some comments I would make are that Nifty is a great example of an awesome orebody ruined by poor planning, execution, and greedy/short-term managers. Winu and Haverion are relatively new discoveries with eye-watering startup capital costs due to their deep cover, extremely remote location etc Degrussa and Monty are good examples of extremely high-grade orebodies that can make a lot of money, super high grades can solve almost any problem. Degrussa and Monty are legitimate "company maker" mines. The last one you mentioned called Liontown near Charters Towers in North QLD is possibly better lumped together as the Thalanga Group of mines and it has a colourful history going back to the 1970s and challenges with grade, an old mill, geotechnical ground conditions