Hi Salpetie,
My skills with re grade variability go no further than yours, and you tell it far better than I could.
I've done my time in mining, open pit and mainly underground, but I am very much a structure/lithology/conceptual exploration geologist at heart.
Minyari and WACA have frustrated me in the past, because I couldn't see clear potential to expand them along strike, given the amount of shallow drilling that appears to have already been completed. And I also thought both deposits looked very steeply-dipping, and appeared to be heading out of range of an open pit.
But since Havieron has been found, that has changed everything. It is now apparent that the real potential at Minyari and WACA could be beneath the known mineralisation. If you take the cover off Havieron, as you know, it is a laterally-confined, steeply-dipping, almost pipe-like body. In terms of shape, it has more in common with the Tennant Creek high grade copper-gold orebodies than with Telfer (although that is also a vertically arranged in its own way).
So what really encourages about this recent release is that, having got some deep diamond drill holes into Minyari, they can now see that it really does look very similar to Havieron. It is a similar style of breccia-dominated mineralisation. It has similarly steep-dipping localised structural controls. It occurs in similar host rocks. And it appears to have formed at a similar stratigraphic level . Plus, importantly, there appear to be some very similar the high-grade sulphide breccias at Minyari, that are analogous to the rich 'sulphide crescent' breccia mineralisation at Havieron. This presents a very attractive discrete geophysically-traceable drilling target. Imagine if they have just nicked the edge, or the top of something like that.
I also like the analogy that they are drawing in terms of the development at depth and the zonation of the mineralisation. We don't know what the upper part of the Havieron system looked like because it has been eroded away and replaced by Permian cover rocks. But what they appear to be observing at Minyari is that the deeper they drill, the more it starts to look like the deep-seated Havieron mineralisation.
Given that the Havieron is close to Minyari, and that it appears to have formed on exactly the same regional NW-trending geological structure, and to lie at the same level in the stratigraphy, it is certainly possible that both Minyari and Havieron, (if contemporaneous), may have formed at the same structural level, at similar original and current depths, and could be similarly vertically zoned in terms of mineralisation. If this is the case, then Minyari may indeed develop downwards into a Havieron-type gold deposit beneath its currently-drilled shallower mineralisation.
And if so, beauty of Minyari would of course be that, whereas Havieron has had the top 400m of the orebody stripped way by erosion and then been buried by a 400m thick layer of worthless waste rock, that somebody has to spend a fortune digging out or declining down through to get at teh underlying orebody, Minyari is mineralised right from the surface. With Minyari, you would be making money, or at least defraying a major part of your development costs all the way down from the surface to the underlying major deposit.
Agreed it will be quite some time before next week's diamond drilling program completed and produces results, but there should be plenty more news-flow generated by the other JV partners in the meantime, plus RC pre-collar assays and deeper RC drilling exploration results from Minyari-WACA itself. And they should have an RC rig on-site already to do the precollars. Plus it helps that Minyari-WACA results come directly from AZY to the market, without the intervention, delays, screening and internal politics of a large, unhurried, risk-averse JV partner.
Time to get back to my day job!
With regards,
Onceover.
