Hi F,
Lots of thoughts - hope some are of use.
From your post I get the impression you think this is the first hole into a new discovery. I doubt that is the case but the comments below come, in part, from that assumption.
Much of what is below is also a rephrasing of this previous post.
Sulphur Springs (SS) was discovered some 25 years ago. Since then SS and the area have been explored with drilling locally to some 500m. As is common for this type of deposit (Volcanic Massive Sulphides (VMS)) there are a number of similar deposits recognized in the area. At present SS is the largest and most explored.
From personal experience at Golden Grove (VMS east of Geraldton WA) the initial sexy holes are those with high grade zinc and copper sulphides that attract more attention than the near surface oxide/supergene copper. The latter tend to be a blanket over the deposit and while they can be higher grade are generally relatively small over VMS mineralisation.
At Gossan Hill there were two supergene deposits known by the early 90's. I heard they began mining the Cu rich one (?<1Mt ?grade Cu (malachite and chalcocite rich with local spectacular grades) possibly around 2010? but haven't heard about any development of the Au/Ag rich one which was more borderline for economics. Grades in these sub surface blankets/zones: locally 30+% Cu, 100+ g/t Au, 5000 g/t Ag.
Note these grades are mostly very local and can have a major influence on weighted averages within drill intersections.
I expect there will be some very high grade values in the 5.5m zone of VXR's Hole 90 where sooty chalcocite mineralisation has been announced.
The important aspect of such patchy high grade is whether it is statistically real and that can only be determined by fairly dense drilling and sampling. The type of sample Novo are doing at Purdy's is for what may be an extreme end member of very patchy mineral distribution.
This drilling at SS will tell if the Cu grades in the supergene zone can be estimated with sufficient confidence or if more work is required.
What VXR have at SS is evidence of a supergene mineralisation at the interface between the weathered and fresh (sulphide) part of the deposit based on past drilling. This zone is like the cream on top of a cake and, if confirmed, will likely positively impact on the economics of the main part of the cake at depth where the sulphide ores are lower grade but significantly larger in volume/tonnage.
Supergene oxide inferred 800,000 tons at 4.2%
Sulphide 13.4 Mt at 1.5% Cu + Zn and other credits.
I was a little surprised by the grade in Hole 89 having seen these core photos and the average grade of the deposit. Even with actual core it can be difficult to estimate grades but toss on an oxide/chalcocite component and it becomes more difficult.
View attachment 786078
This section shows how the drill results appear relative to each other and interpreted geology.
View attachment 786087
The variation in Cu grade in the supergene zone is hinted at in this section by the grades reported for Holes 89 and 34.
Hole 89 - 38m 3.49% Cu: made up of a maximum of 9% Cu within 14m of 6% Cu - which means the other 24m (38 -14m) grades around 2% as a weighted average (closer to the deposit average Cu grade but still elevated). No Zn/Ag/Au reported yet?
The nearby historical Hole 34 has 21m at approximately 3% Cu and 3% Zn.
Such variations are to be expected and would have been taken into account for the inferred supergene oxide resource. As drilling being done to confirm that resource 38m @ 3.5%, while good, could slightly reduce the grade but perhaps increase volume. One result with another 16? to come so early days.
As you note Funkbunger it is good to see the Au/Ag intersection in the leached portion of the hole.
View attachment 786147
If it is anything like the Gossan Hill Au/Ag enriched zone and can be mined as part of the overall operation it could be a value adding portion of the deposit.
Metallurgy on the various deposit styles (Oxide Au/Ag, supergene Cu, sulphide Cu/Zn) will have to be worked out to assist in any economic assessment.
A lot of waffle above but IMO comparing SS to Degrussa is not a good thing for
overall grade.
The Degrussa and Monty deposits are AFAIK in the upper quartile for Cu grades in fresh sulphides. Also there was Direct shipping ore (DSO) produced from Degrussa (may have been supergene) with grades in the 8-18% range.
At Sulphur Springs the Cu grades are much lower in both the supergene (approx 4% vs ~8-18% SFR) and primary (1.5% vs 3-6% SFR)
This image is from a November 2010 SFR presentation which gives some numbers for the relative size of the oxide and primary resources at the time.
View attachment 786207
The ratio of oxide to primary (fresh sulphides) mineralisation is always going to be low because the vertical extent of the oxide zone is usually way less than 100m (0-??50m at SS) versus the primary sulphides which extend to +500m at SS (or 2500m at say Kidd Creek in Canada without any oxides because of glaciation).
As an aside: The Degrussa high grade DSO led to significant royalty discussions with the WA government who considered it in the category of bulk mining (c.f. Iron Ore) and wanted to impose a higher rate. Just one of many unexpected/possible factors that impact on economics. I don't know the final result of the 'discussions' - not pertinent here.
Some late weekend grist for the mill. Most derived from musings of fun times at Golden Grove and a broad interest in exploration without much detailed research so DYOR.
GLTAH