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Tuesday, November 28, 2017

SolGold: regional exploration

DISCLOSURE: I own shares in SolGold 

In between PRs about awesome drill results we got this one (link) showing some results from their regional exploration on their Machos-Florida Santa Cruz-La Hueca concessions in Southern Ecuador.

Dear SolGold - the La Alumbrera Mine is Miocene in age (~7Ma), not Jurassic (145-201Ma). So they don't get any cool dinosaurs (e.g. Chilesaurus (link), just Terror Birds, and check your scale bars, they are wrong.


Summary


  • Good address - large property package located in the Jurassic porphyry/epithermal belt in Southern Ecuador (Mirador and FDN)
  • Good initial results - Regional sampling has identified 3 areas of interest
  • Follow-up rock-chip sampling identified an initial area with good indications of porphyry mineralization.
So it is early days, but SolGold have hit the ground hard, applied a logical exploration strategy when working on a large property. Start big, do regional sampling to identify areas of interest, and then focus on them.

Location, location, location

As I've mentioned before, porphyry/epithermal deposits occur along belts, and in Ecuador there are 2 principal belts:

  1. Older Jurassic Belt - hosts Fruta del Norte (14Moz Au) and Mirador (890Mt @ 0.56% Cu and 0.16 g/t Au)
  2. Younger Miocene Belt - hosts Cascabel, Junin etc.


So, if you are looking for these types of deposits, these areas are where you want to be, and SolGold's concessions are located in the Jurassic belt. They have acquired a large property (~25km x 10km), and unlike many exploration companies, have actually conducted a logical exploration program to quickly evaluate the property and identify areas of interest for follow-up work.


Stream sediment sampling

This is used to quickly evaluate large areas to identify areas of interest for follow-up with more detailed sampling. The idea is that if a deposit is exposed at surface, it will be eroded and indicator minerals (gold, magnetite etc.) will go into the silt, sand and clay in a stream or river bed.

Each one of these horrendously colored polygons is a drainage basin
SolGold have collected 180 stream sediment samples, probably 1-2 per basin, that have identified 3 principal Areas of Interest (AOIs).

2 small and a biggie, the red outlines are highlighting core areas (I think)
Just from collecting 180 samples, we can see that >80% of the property appears to have a low potential to host porphyry Cu-Au mineralization. This probably costs SolGold ~ US$20K, and has identified 3 areas of interest where more detailed (i.e. more expensive, more time consuming) exploration can be conducted.

The key is to identify areas with potential and not get distracted by the areas without. This is very unfashionable as a typical Junior exploration company will simply amalgamate concessions and do nothing with them.

Prospecting and sampling

After you have defined your AOIs, now you have to visit them to see what you've got, and it is this basic prospecting (i.e. looking for evidence for mineralization) that we are given in this PR.

Now, before you all go weak at the knees at the assays and photos, let's take a step back. SolGold have told us that they have ~470 rock chip samples, but this PR is only giving us info from just 46 samples (~10%), why? Are these:

  • The greatest hits?
  • The 1st batch, with more results to come?
It is obviously the former, figure 3 in the PR tells us that in the other areas they sampled disseminated chalcopyrite with low grade copper gold mineralization. 

We are also told that there is biotite alteration, this is typically found in the (potassic) core of a porphyry system, and it can be a bit of a double-edge sword, as this is where you typically get the highest grades. This is also characterized by the presence of bornite. However, if the samples collected from this area are not very high-grade, is this an indication that the porphyries are not well mineralized? This is a rhetorical question as it can only be answered by the truth machine (the drill-rig).

 mineralization, but if these samples aren't very high-grade, this may indicate that the mineralization 

We can also see where these samples have come from, they are shown on the map above, but why don't we zoom in a bit. 

Left = Copper; right = Gold, the red circle is 1.2 km wide
We see a cluster of samples, some nice high-grade ones, but the majority are low grade, which isn't unexpected at this stage.You also have to remember that most rock-chip sampling is biased, the pretty rocks get sampled first, so they aren't really representative of the overall grade of the rocks.

So it is a good start from SolGold, they have identified an interesting target with decent initial results. At this stage all you should be reading into this press release is that SolGold have found evidence for porphyry-style copper gold mineralization on their new concessions. It is a good start and I hope to see more information from SolGold on their regional exploration activities.



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