I am not convinced that there will be a super-duper discovery hole here at Bottletree, just as happened with AGC or other explorers. The best one, or up there with the best, was Sandfire's fabulous vms copper/gold hit in 2009.
I think that the writing is on the wall already that Bottletree has the potential to produce minable ore with the wall rock copper already found. More wall rock ore has to be found of course. Many big porphyry mines eg Cadia were created just with wall rock mineralisation. The core (potassic) was never found.
It is hoped though that CEIs 1 and 2 will find something better than wall rock by hitting the core of the porphyry system that created the wall rock. What that might be is the big question. Will it be rich? Will it be poor? Regardless of whether rich or poor or even indifferent, finding the core should help with exploring around it.
That is a complete guess on my part though as I have no experience with porphyries apart from SPQ's. I have read about porphyries both specifically and generally hoping to find out what might be in the core and what is the benefit of finding and piercing it but have not come up with anything worthwhile as yet. Could someone who knows post on the subject please.
We have been told that both Bottletree and Cockie Creek are 'reduced porphyries'. Various reports from SPQ have explained what that means {see one such below). It is neither bad nor good so far as i can tell. It is just how it was created. Bottletree and Cockie Creek have copper exceeding gold by a long way, but I understand that Steam Engine's gold was created by a porphyry system by being a distal deposit of 'vapourised' gold coming from a porphyry system not found yet.
As regards 'reduced' and 'vapour-phased', read this extract from the 23 April 24 announcement.
The reduced nature of the sulphide mineral assemblage (pyrrhotite-bearing) and associated hydrothermal alteration (absence of primary anhydrite, gypsum, and hematite) in meta-volcanic wall rocks is consistent with Bottletree forming from relatively reduced hydrothermal fluids associated with a reduced I-type arc magma. The Cockie Creek Cu-Au-Mo Prospect has similar mineralisation and alteration features and both it and Botletree are consistent with classification as Reduced Porphyry Cu-Au (RPCG) systems (see ASX 10 announcement on 31 January 2024). The term “reduced” applies to the oxidation state (or oxygen fugacity) of the causative magmas and associated magmatic-hydrothermal fluids (Rowins, 2000).
These mineralogical differences with the more oxidizing porphyry systems with abundant hydrothermal magnetite will affect the strategy used for exploration targeting. Specifically, there are differences with the magnetic properties of the mineralization (i.e., only minor hydrothermal magnetite but abundant magnetic pyrrhotite), and displaced and expanded geochemical anomalies in soils due to the likelihood of enhanced vapour-phase transport of Cu and potentially Au from the magmatic source (Rowins, 2000).
SPQ Price at posting:
0.9¢ Sentiment: Buy Disclosure: Held
(20min delay)