Anta Kori Update

I haven't been following Regulus to closely for the last 6 months, but I decided to compile the new drilling data (link and link) and see what they have been finding, and how the new drilling may impact the overall resources for the project.

Background blurb:

The original resource for Anta Kori was done waaaaay back in 2012 for South Legacy, but if you read through it, it is very light-weight, we don’t get any information on:

• Where the resources are located – not even a simple map
• Where are the open-pitable resource located?
• And the underground resource? Where is it, how will they mine it, from the bottom of the pit?
• No images or sections of the block model showing grade distribution etc.

It is a crap report, a quick and dirty resource calculation. I especially hated the way that they used every metal under the sun to calculate the CuEq grades for the various resource cut-offs.

In essence, it is a crap report.

However, table 14.7 did give a breakdown of the global resources (i.e. not constrained by property boundaries). I wanted to see if I could create a base model from the historic data that could match it, with the idea that I could bring in the recent drilling results and see what happens.

However, I have a big problem:


 
Look at this table in detail, start with the first row. Write out the total contain metals in full (i.e. including the “0” in the column headings. Do you get:

• 519,541,000 tonnes or ~520Mt that contain
• 4,429,000 lbs of copper – just 4.4Mlbs
• 126,335,000 oz of gold – 126 million ounces of gold 
• 3,989,155,000 oz of Silver – just under 4 billion ounces of silver
• 10,598,000 lbs of Moly
• 572,695,000 lbs of Lead
• 2,172,276,000 lbs of Zinc

Damn it, Southern Legacy found South America’s largest gold deposit and second largest silver deposit. Who gives a shit about copper with all that lovely gold and silver.

Unfortunately, as I’m an idiot, I decided to try and work out WTF was going on, brought the data into excel and calculated the amount of contained metal for each element (basically took the tonnage and multiplied it by the grade provided).

And you get….



There are some slight differences:

• ~30% reduction in contained copper (assuming the table was referring to Billions pounds of copper).
• ~45% increase in gold (I have assumed that they put the contained gold under the contained silver column)
• Silver, lead and zinc stay the same (assuming that the contained silver was put under the contained gold column)
• ~80% drop in contained Moly

Generally, very painful news, but the extra couple of million ounces of gold is a nice bonus.

The silly thing is, table 14.5 that splits the resource into Open Pit and underground areas, i.e. the one on Regulus’ website is fine.
 
WARNING: These guesstimate calculations are complete BS. They are based on grade only, and are designed to give a feel to what Regulus have added to the project.

This is a global guesstimate, I haven't split out mineralization by type, I have assumed everything is the same, which we know is wrong as the high-grade intercepts are restricted to narrow, sub-vertical breccia bodies and veins.

I've included a Leapfrog 3D viewer file here of the various iterations (link)

Notes:
I’ve used the CuEq values, but in the recent drilling these have been calculated from Cu+Au+Ag only, not everything including the kitchen sink as used in the 2012 technical report.
I haven’t factored in mining type, property ownership or recoveries. I’m treating it as a single deposit, calculating the global resources and then clipping it by property boundary to see how much is in Regulus’ concessions..

TAG Guesstimate Global Historic resources

So we get close, I have slightly less tonnes and a slightly smaller CuEq grade (0.48% vs 0.51% from the 2012 technical report).

When we compare the drilling we can see that Regulus have done a lot of work.

Before Regulus:
 

Regulus:

lots more copper intercepts

We see a lot more holes, drilled to much greater depths exploring for the Skarn mineralization that was of secondary interest to Southern Legacy who were mainly focusing on the near surface high-sulfidation gold dominant mineralization.

So, what impact does that have on the project ‘resources’?

 

Potentially a lot.

WARNING: I've assumed that all the mineralization is the same, I haven't separated by skarn vs HS vs breccia vs vein. It will be an over-estimate.

If we clip it by property boundary:



We see that the majority is on Regulus’ concessions. This is biased by the fact that they can’t report the intercepts that do not occur on their concessions. 
However, when we put the global resource figures on the USGS Porphyry Copper chart we see this:



*CuEq figure form the 2012 Technical report, but just using Cu, Au and Ag

If we look at the global resources, the average grade of Anta Kori wasn’t quite good enough. However, if we look at the high-grade (>0.5% CuEq) core of the system, we see that the project changes completely.




It now sits firmly in the ‘good’ area of the chart.

TL:DR version

Regulus have done a lot of work at Anta Kori that should lead to a decent jump up in resources. The key here is to look beyond the overall tonnage to see how much high-grade (>0.5% CuEq) material they have.

An important question to ask or at least think about is - How will Regulus report their upcoming resources? With the agreement with Coimolache allow them to report a global resource or will they only be able to report the mineralization that occurs on their concessions?
An Observation
On the plan map that accompanies the last PR we see hole AK30 sitting way out to the NW all on its own. Why did Regulus drill such an anti-social hole?





If we look a bit closer we see that the hole starts on Coimolache ground, suggesting that Regulus are still working with the Coimolache permits. This may mean that they still haven’t been granted their own permits to drill in that area.



It looks like the hole is testing the contact between the limestones and porphyry, but without a decent surface geology map to help, it is hard to know why they have been drilling ~500m to the NW of the known mineralization. It is a low risk hole, if it gets something, then they’ll have expanded the footprint significantly, but if it gets nothing, no-one will really care.

AntaKori Update

I've been (slowly) working on a series of posts reviewing several porphyry projects, highlighting that many are very small or just too low grade to really bother with, but I decided to go back and update my AntaKori model, with the recent-ish drilling results (link) because I've had this nagging feeling that AK was the same - not quiet good enough.

I plotted its resources on the USGS Cu chart of doom with updated CuEq figures using Regulus' CuEq calculation shown intheir PRs, which, unlike the 2012 43-101, doesn't include any credits for Mo, Pb or Zn. Doing this decreases the overall CuEq grade from 0.92% to 0.83% CuEq.



So, my gut-feeling was wrong, AK is good enough, but has there been any change with the new drilling?

Here is an officially bad calculation for the AK resources that occur within the Regulus mineral licenses. You can get the Leapfrog viewer file here (link).

~11Mt extra tonnes at the same grade

That's disappointing, but the grade has stayed the same! Small victories!

Why wasn't there a drastic change? The drill results have been impressive, but unfortunately, the drilling has been directed by Coimolache who are focusing on extending the high-sulfidation gold mineralization they are mining to the west, and had not been focused fully testing the skarn-porphyry potential at AK.

However, hole AK-18-007 may be changing that. Most companies won't drill a 1400m deep hole costing ~$0.4M if it wasn't hitting something interesting (unless they needed a lot of novelty knife sharpeners for the Lima Gold Symposium). Unfortunately, we'll never see the results, but we can do some arm waving.

Here is the hole plotted against Kev 'n' Stu's geology section...

A 1400m drill-hole drilling nothing, I don't think so.... 

Oooooooohhhhh, the 700m interval that Regulus have seen, fondled and probably licked, lines up quite well with that flushed Miocene Porphyry (same age as Antamina - 900Mt @ 0.99% Cu) intrusion thrusting powerfully through the hard rocks of northern Peru.

Why don't we have a look how this hole relates to the other targets defined by Regulus?



I've borrowed the Intense magnetic image from the latest presentation, not just because it is pretty, but looking beyond the hot color stretch we can see that hole AK-18-007 was drilled between the 2 bestest-ist porphyry-skarn targets (# 1 and #2) on the property? Regulus already have a decent sized target that is basically the sweaty armpit of a well mineralized district. I'm hoping that they can get some rigs exploring the blue nipple (target 1) to see what is causing it.

The red-stuff is just skarn and no-one cares about that.....

Regulus - Antakori update

Just a quick update, a couple of weeks ago some additional assays were released by Regulus from Antakori (link).

Summary

• Drilling restricted to the edge of the property
• Focus on HS-epithermal system by Coimolache - drilling to extend pit resources
• It is going to be interesting to see some drilling in 2018 designed by Regulus
• Arsenic restricted to the Intermediate Volcanics and the HS-epithermal mineralization.
• Minimal As in Skarn zone.
• Thick, but relatively low-grade Cu mineralization hit by hole 17-161 extends the limits of the Skarn mineralization by 400m to the SE, but the elevated Zn and decreasing Cu indicates that it was drilled near the edge of the system.

I've brought in the new data into 3D and run it through Corebox's Drill Hole Interval calculator, and built a 3D model, that you can download it from here (link - note: it is 63MB in size). I want to see how the Cu, As and As are related.

DISCLOSURE: I have used the assay information from Table 2 as it includes assays for Ag, Zn and As. Its intervals are slightly different to Table 1, from where the press release headline was is referencing, so there will be slight differences.

Geology

We can see that all the 2017 drill-holes have come from around the SW margin of Regulus' concessions. When we overlay this information onto a satellite image we can clearly see that the drilling by Coimolache is focused on drilling the extensions of the High-Sulfidation (HS) epithermal mineralization that they are currently mining.

Black = 2017 Drill-holes

Results are focused along the SW margin of the Antakori concessions, it looks like Coimolache are focusing on drilling the extensions of mineralization currently being mined.

Here are a series of sections from the latest results.

Section - L1050NW - Drill-hole AK-17-003 and 003A

Copper

We can see that the highest copper grades (>0.25%) appear to be found at the contact between the HS-epithermal (in the Light-green Upper Volcanics) and the skarn mineralization (in the Light Blue limestones), and are the discrete >0.25% Cu zones restricted to the narrow, intrusive dykes (pink and red units)?

Gold

It appears that all the gold mineralization is found in the upper HS-epithermal zone. Minimal gold appears to be found in the intrusive rocks).

Arsenic

Here we see As is restricted to the upper HS-epithermal zone with minimal As in the Skarn.

Section - L200NW - Drill-hole DHSF17-161 and AK_17_004 (results pending)

Copper

Again, Cu is restricted to the Skarn (limestones). It is generally low grade, around 0.1 to 0.25% Cu, but there are a couple of narrow, high-grade (>1%) zones that appear to be associated with either the old breccias or narrow Young Felsic units. In the NE, several short holes have intersected narrow Cu-Au mineralization associated with narrow, massive sulfide veins.

Gold

Minimal gold was intersected by hole 17-161, this hole didn't intersect HS-style mineralization within the AK concessions. It will be interesting to see how much HS-mineralization will be hit by hole  AK_17_004.

Arsenic

Again, minimal As is found within the skarn units.

So you can see that the Cu grades are gradually decreasing to the SE, and the elevated zinc assays seems to indicate that hole 17_161 was drilled into the peripheral part of the large Antakori skarn system, suggesting that the high-grade core is probably located to the NW.

Ankakori - the first hole

DISCLOSURE: I should have bought more

What a whopper! A great first hole from Regulus at Antakori (link). They have been very intelligent and the initial drilling is focused at filling in the gaps left by [insert name here].

You can download the 3D model from here (link) - please not that this file is big, I've included the topography and overlain the property boundary and some geophysics in the 2006 technical report.

Summary

• Antakori is a complicated multi-phase mineral system. dominated by:
• High-sulfidation Epithermal - Au, Ag, Cu and As rich
• this is what is mined by the neighbors to the SW
• Skarn/porphyry mineralization - Cu +/- Zn, Ag, Pb rich
• Great first hole, plugged into a nice high grade zone identified back in 20XX
• Mineralization is Epithermal (high-sulfidation) - hole will be Enargite (Cu-Au and As) rich
• AK-17-001 didn't go deep enough to test the skarn/porphyry potential, but hole AK-17-002 will!

Hole AK-17-001, 002 and 003 have been drilled along the SW margin of the property, where it butts up against the Tantahuatay Mine.

my annotations - is that mag low to the north a porphyry?

 Hole AK-17-001 went smack between historic holes SDH-034 (120m @ 0.63 g/t Au and 0.67% Cu) and SDH-037 (188m @ 1.07 g/t Au and 2.02% Cu) drilled in 2012, and demonstrate that this zone appears to be quite high-grade and robust.

here is a cross section

pink = HS-epithermal domain; blue = skarn domain

You can see where hole AK-17-001 has hit, the copper grades are very good, but the gold is restricted to a narrow (23m core length or ~ 10m true width) zone grading ~ 7 g/t Au with a lower grade halo, suggesting that there could be some high-grade veins in the core of that hit.

And a long section with some distances on it.




Why don't we take a bit of time to look at the Antakori property. To steal a football pun, it is a project of 2 halves:

1. High-sulfidation Epithermal deposit
2. Skarn-porphyry deposit

HS-Epithermal Mineralization

This is what they are mining next door and looks like this:

Dickite, hehehe

The enargite is the issue here, it contains arsenic, and historically this project is regarded as having an arsenic issue. It does, but it is local, and it will be a problem for the neighbors if (when?) they start expanding the open pit into this area (with a nice NSR to Regulus is they do!).

The Skarn-porphyry mineralization

Simple formation model - Porphyry + limestone = skarn

Peru has a few big 'uns (Antamina, Las Bambas, Tintaya etc.) that produce a lot of metal. The historic drilling has hit some skarn, but it hasn't been drilled systematically, and this is where a lot of potential for AK is. I was a bit disappointed that hole AK-17-001 didn't go deep enough, but a minor grumble.

It looks like this:

doesn't look impressive, but can be big!

However, hole AK-17-002 should be going a lot deeper properly looking at the skarn potential at Antakori, and is the hole I'm interested in!

So, early days, but it is good to start the 2017 drilling with a nice hot hole. A bit of a cheat (focusing on infilling a known high-grade zone, but might as well test the lowest risk targets to get the juices going.
However, I have a few questions:

• How much input do Regulus have in this drilling campaign, are they restricted by their partners?
• Do they have permitting to explore the entirety of the project or are they restricted to specific areas?
• Why are they drilling that gold project in the US?

This is going to be an interesting, developing story, I'm happy with the first results and would like to see some evidence of regional exploration (cheap, low-end stuff), and maybe some geophysics to see if there are other decent targets in the area.