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Many thanks for the reply PGE_Geo. GLA
Thanks for your thoughts PGE_Geo. I found the title 'Drilling Intersects Massive Copper Sulphide Mineralisation' interesting as I could find very few references to 'Massive Copper Sulphide' on the internet.
Sorry should have said: ...nickel and zinc mentioned by fulmar...
Hi everyone,
Sorry about the slow response I was running errands.
Ella, I can 100% see where you are coming from, however there are three possible reasons why they described it as ‘massive copper sulphide mineralization’: 1) It is common when describing a sulphide ore that you will focus on the primary ore mineral(s) when discussing the ore, so in this case even though the sulphides are possibly dominated by iron sulphides the actual mineral we’re interested in is the chalcopyrite, so calling it massive copper sulphide is acceptable. 2) the majority of the ore is dominated by copper sulphides and the piece of core shown in figure 2 is an anomaly, which was selected because it shows some good quality massive sulphide, or 3) I’m completely wrong in my identification, there are plenty of idiots with advanced degrees in the world and I might be one of them.
We know that the Domes region of the copper belt has been deformed in a significant way at least twice (once extensional and once compressional) leading to folding and faulting. We also know that a substantial portion of the mineralization in this region is the result of remobilization of metals by hydrothermal fluids, this differs from the eastern end (the classic Zambian copper belt) and the western end of the Congolese copper belt where a substantial amount of mineralization appears to be primary (although sometimes metamorphosed/structurally reworked). I can’t remember who it was (maybe SeisNav) but someone mentioned how the fluid flow will exploit the fault zones, so the oxidized zones may well represent sulphides which were remobilized from lower levels, moved up the stratigraphy via the faults, were redeposited and then eventually exposed and oxidized, with the faulting being the primary control on where the mineralization was heading. This obviously means that the sulphides need to have come from somewhere and it is this material that I feel Arc and AA were interested in, hence the deeper drilling. The remobilization will have moved a range of elements up through the strata including the nickel and copper mentioned by fulmar and even given the correct fluid chemistry gold as pointed out by SM. Uranium chemistry is outside of my knowledge base so I’m going to bravely ignore it, sorry SM.
I tried to get smart editing the url
Try this
https://www.google.com/amp/s/www.miningreview.com/base-metals/arc-minerals-making-strong-headway-in-zambia/%3famp=1
Don't forget uranium!
https://www.miningreview.com/base-metals/arc-minerals-making-strong-headway-in-zambia/%3famp=1
”“I believe that there could be nickel deposits on the eastern side of the project while there have been traces of gold found on the west side. This has resulted in a mini gold rush in that area.
“Also, we have found traces of uranium which is often link to gold. So while, our focus is on copper, I will not be surprised if we discovered other metals during our exploration,” concludes Von Schirnding.”
Do I really think we're sitting on a ton of uranium? Not really but it is interesting to revisit that article.
surface /ground samples of Fwiji have indicated Nickel and Zinc,and according to one JM@SPA a possibility of gold, but obviously grades/assays yet to be seen .
Hi PGE_geo,
The RNS title refers to massive copper sulphides rather than just massive sulphides containing copper does this not imply that the rock is majority copper sulphide?
Hi Daniel,
Figures 2 and 4 just show sulphide mineralization, alas no visible gold. Figure 2 shows some nice massive sulphide in the top half of the core, the lower half of the core is a little less clear, but it looks like it contains more fragments of the wall rock, so I would classify it as "stringer" style mineralization. If you look at the massive sulphides there are two distinct colours, a light gold coloured mineral which is likely chalcopyrite (copper iron sulphide) and brown-gold coloured mineral with a hint of pink, which is possibly pyrrhotite (iron sulphide). My pyrrhotite ID may be incorrect as the red colour of the soil may be influencing the colours I see. If it is pyrrhotite I would expect some nickel to be present in the assays, as nickel is a common impurity in pyrrhotite, however extracting the nickel from it is a pain and rather expensive when compared to a standard nickel ore minerals like pentlandite (nickel iron sulphide), so chances are it would not be economic to extract if it is present.
Figure 4 is a bit more difficult to call, it is most likely pyrite (iron sulphide), but fresh untarnished chalcopyrite can also have a similar appearance, however pyrite is more likely. This would be consistent with the standard hydrothermal ore assemblage which is typically dominated by pyrite, with lesser chalcopyrite, sphalerite (zinc sulphide) and galena (lead sulfide).
The exact copper grade for each sample is difficult to gauge. They were right not to give the XRF values as there is no way for us to know whether they preferentially analyzed more copper rich parts of the core to get the best values possible, also sometimes called high grading. They are wise to wait for the assay results which will be from homogenized samples as it provides more realistic values. Once we have that data we can calculate the sulphide composition of the core.
not a geologist, but in figures 2-4, are the gold coloured parts Iron pyrites (fools gold) or actually gold. Cheers, Dan. GLA
Arc Minerals has just tweeted:
"#ARCM This is the most significant copper sulphide discovery since we started drilling 4 yrs ago. Initial XRF data indicate significant GRADES of copper mineralisation - a potential GAME CHANGER for us. I look forward to an EXCITING PERIOD for Arc shareholders." [Typed by ARCM]
Screen shot by ARCM : The intersection of MASSIVE SULPHIDE copper mineralisation provides strong support for B I G MINERALISATION S Y S T E M S at play & provides a marker horizon for further targeting. We are currently reviewing & EXPANDING OUR DRILLING & airborne geophysics programme. Nick von Schirnding, Director & Executive Chairman." [Pic shown]
Time of tweet by ARCM on Twitter: 10:43am, Fri, 24 Sep 2021.
https://twitter.com/ArcMinerals/status/144133745154289168
Teaye72 also spotted it on Twitter. I am posting the details of the tweet for my own record given I posted about the "massive sulphide mineralisation" RNS of 21.9.21 below and it is good that ARCM themselves have just posted and tweeted.
https://twitter.com/ArcMinerals/status/1441337454154289168?s=20