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.