FMF - Friends of Minerals Forum, discussion and message board

[Pierre Joubert]

Hi Steve. Nice article! What a nice outdoor experience! I envy you. Wishing you all success.

[crocoite]

I wish Pierre! The closest I got was having Dehne and Maureen here last night for dinner on their way back to Tasmania!

[Pierre Joubert]

[BlueCapProductions]

Great posting. Thanks Steve!!

[Don Lum]

Steve,

Thanks for posting. Really enjoyed the comments and pictures. Well done.

Regards,

Don

[Jordi Fabre]

[crocoite]

From Dehne McLaughlin, the First Newsletter May to early June 2016 about the Malbunka Copper Mine Project (MCM Project)...

Enjoy!

[crocoite]

This newsletter is the first on field work undertaken in 2016 in the desert of Central Australia at the Malbunka Copper Mine by Dehne and Maureen McLaughlin for the recovery of discoidal azurite specimens on white kaolinite matrix described as “azurite suns”.

We set up the mine camp and advanced our down dip drive by 0.5 metre in late April 2016. As you can see by the photo below, the mine camp has had a growth of tents, accompanied by separate mini tents for men’s’ and women’s’ portaloos. This was bought on by an increase in workers, visitors and visitor/workers who wished to experience the mine site this year. All our water, food and fuel has to be bought into the mine site with our 2 4WD trucks along a rugged bush track so we work a 6 night mine and 4 night Alice Springs roster.

[crocoite]

The weather was hot due to our early arrival at the mine so we did not overburden ourselves with too much waste rock removal. Dehne was limited to 12 shovel fulls to a barrow load. The down dip drive at this stage of development was a suitable scale for seniors and turned up specimens dominated by ~1 inch diameter suns on matrix in small to large plates. This was a pleasant surprise as we did not mine this face in 2015 due to lack of man/women power and wondered how it would turn out. The up dip face was running into problems in 2015 as advised in our last newsletter so alternate development faces needed to be revisited.

We had a break away from the MCM for 12 days and despite some serious vehicle problems, Dehne went off to the Mud tank zircon field to catch up with an old digging friend, Ivan Dainis.

Unseasonal rain at the field nearly trapped Dehne at Mud tank but he escaped back to Alice Springs to prepare for our second field trip to the azurite sun mine. On arrival back at the site, we found we had not put our storm water dam in place in the main adit and water had run into the decline. The land was in drought when we left it and of course it does not rain much in the desert!

[crocoite]

On this second trip to out we were accompanied by Joshua a young miner from Alice Springs, who demonstrated how waste rock should be mined and moved. Once we had advanced another 0.5 metre into the Down Dip drive (DDD) Maureen and I undercut the azurite bearing formation while Joshua cut a vertical wall in preparation to undercutting the UDD.

Specimen recovery again was reasonable in the DDD and it took us 3 days to complete the collecting in this new cut due to the presence of not only a productive L1, L2 and L3 horizon, but also a frequent Lo horizon below L1. See PHOTO 3 below.

[crocoite]

...

[crocoite]

We identified a new sedimentary dyke in the DDD, the largest to date, that has been injected into the kaolinite and siltstone layers at a shallow angle. It crosses half of the 5.5 metre working face and has been continuous down the anticlinal dip for over 4 metres. It is comprised of silicified hanging wall sandstone and angular hardened kaolinite pieces with fine atacamite crystals in fractures in the sandstone. Good micros.

[crocoite]

Eric Melchior and Dehne have spent a lot of time developing an argument for azurite mineralisation and ground preparation bought on by hydraulic overpressure in the sediments during compaction and dewatering at a depth of over 300 metres (world’s first example). With several other specialist authors we submitted in April 2016 a paper to Mineralium Deposita in Europe. Clay and sandstone injectites along with natural hydraulic brecciation synchronous with azurite crystallisation is featured in the paper. This injectite has also been identified recently in the end face of the main adit and combined with reinterpretation of the azurite bearing horizon from DDD lithologies has changed Dehne’s ideas of where the azurite concentrations are heading.

We were accompanied on our third trip to the mine over May 23rd to 29th by Craig Bosel of Perth. The three of us did a half metre undercut into the UDD prepared by Joshua across ~9 metres using 3 Makita HK500 hammers with tile lifting type blades. The local gourmet butchers shop in Alice sharpens these blades (you need to know this). We proceeded to drop azurite layers and found that most of L1 and L2 was very poor. Good for azurite paint buyers but not for mine economics. L3 had high azurite concentrations but half of the L3 had highly fractured and silicified kaolinite which also had caused brittleness in the enclosed azurite.

The down dip section of the face down the anticlinal limb across 2 metres had a good L3 showing as in 2015.

In 2015 I advised in the last newsletter that we needed to check out the footwall for azurite mineralisation as this style of footwall azurite is obvious at the mine entrance. The fastest method has been to use the 1 metre long hammer drill steel attached to a 800 watt Makita power tool. Former newsletter readers may remember the photo….”..this is a drill”. Drilling vertical holes beats digging the floor up! So we started drilling 1 metre holes in the deepest sections of the cuts expecting to intersect footwall silicified sandstone based on measurements of the thick clay pillars at the mine entrance. Nada….no footwall silicified sandstone intersections. These results mean a rethink again as we know the footwall “should” be there. The best answer is normal faulting of which we have more than an abundance at the mine. So we will keep on drilling these holes and even if they do not hit footwall they tell us that as the kaolinite lens dips into the hill it has not thinned out……and clay=azurite.

[crocoite]

So by trip 4 to the mine on 2nd June with our Hard Worker Craig, we were quickly back to the productive DDD. On Trip 4 we were accompanied by Michael Grasso and Peter Kellor of Adelaide. Michael’s father had consulted for the mine in the early 1970s and like most of us is keen about wonderful Australian minerals, including azurite suns. Peter is handicapped by a copper mineral bias.

Michael and Peter put in a days work at the face in our underground gymnasium and had 2 great nights on site. Maureen did an excellent job of catering and other social stuff that women do better than men. It was rather strange seeing the boys leave the site in their rental 4WD Toyota reducing mine occupation from 5 to 3. A lonely feeling knowing the mine crew still had 4 more nights to go in the bush.

[crocoite]

But back to work and reality on the DDD where we had started dropping the azurite layers. (in case you are wondering how come there are layers, Dehne advises L1 and L3 are relic thrust fault planes that presented preferred planes of fluid flow for mineralising fluids pumped in under pressure into the dominantly clay formation. L2 azurite deposition is a mish mash of slip planes and original sedimentary bedding).

The DDD stepped up another notch and specimen quality was excellent on all azurite layers. We not only extended the working face down dip parallel to the anticlinal axis, but had also extended the face down the steeply dipping southern anticlinal limb requiring cutting of a stepped floor (Craig Steps). The DDD is sending a message on azurite concentration trends.

Craig and Peter worked on the left hand corner of the UDD where we are encouraged to carry out further exploration. The unfavourable ground has been turned into natural pillar support.

At the time of writing we are preparing for Trip No 5 to the mine. There are food items strewn everywhere in our B and B and the shed is full of stuff that needs to go to the mine, including a repaired electrical fault with a key hammer drill.

Sebastian Strauber is joining us for this trip as our mine worker. Shane Stanfield was to join us for this trip also but due to an important family matter, had to pull out.