Hi Wiz,
As always, thanks for all youâve done and continue to do for Medinah. If the average ore grade at the Don Luis 1 Vein remains at 85 grams per tonne (2.7 ounces per tonne), it wouldnât take that much ore to represent a 1-million-ounce deposit. If you zoom out and look at the entire vein system outlined to date from the Merlin 1 Vein (Caren Mine) to the west and the Fortuna Veins (including the Don Luis 1 Vein) to the east you can easily sense something pretty special going on there. The âplumbing systemâ that allowed the gold-bearing hydrothermal fluids and gases to ascend to the surface must have been very well-developed. The grades at the Merlin 1 Vein area (Caren Mine) well to the west of the Don Luis 1 Vein were also spectacular. The geoscientists have already determined that all of these veins are ârelatedâ. This means that they share certain textures, anatomy and types of silicification accompanying the gold i.e. chalcedonic quartz in this case. The implication is that they probably share a common underlying magma chamber with an average gold grade of âXâ. The gold grade found in the precursor magma chamber can be increased/concentrated if favorable vertical strata are present that promote gold deposition.
A very thorough trenching program already revealed that over 5,000 meters of this vein system have made it all of the way to the CURRENT surface. The CURRENT surface is the original/paleosurface minus the overburden lost by erosion. The erosion process was very favorable here because the various vertical layers of the typical vein complex are all still intact. Oftentimes, in 100-million-year-old rock like this, the gold contents of the vein complex have been eroded and are gone. Theyâre sitting at the bottom of the mountain in placer deposits.
These insanely high grades suggest that this vein complex is sitting smack in the middle of a vertical âboiling zoneâ. This is an area of a vein complex in which gold bearing hydrothermal fluids and gases coming out of an underlying magma chamber are allowed to deposit their gold contents locally. The upward migrating gold is carried in conjunction with sulfur in things called âthiosulfate complexesâ. The act of âboilingâ provides the energy needed to break the bond between the gold and the sulfur which allows the gold to be emplaced in very high concentrations locally. Itâs like a vertical sweet spot within a vein system where the conditions are favorable for sometimes very high-grade gold deposition. It would be very fortuitous if this vertical sweet spot was preserved from erosion and very extensive from west to east. The 5,000 meters of veins making their way all of the way to the CURRENT surface attests to this.
In these âboiling zonesâ the super-heated hydrothermal liquids and gases need to actually cool in order to âboilâ. When rapid cooling occurs as it does in these zones, the type of quartz found in conjunction with the high-grade gold is often referred to as âchalcedonic quartzâ or âmilk quartzâ. The cooling process happens so quickly that the quartz doesnât have time to take on the typical crystalline structure you see in samples. This indeed is the type of quartz prevalent at the ADL where the high-grade gold is being found. Itâs nice when the findings make geologic sense. Whatâs exciting is that these âboiling zonesâ, when present, can be 300 to 500 meters thick.
In order to assess the potential here, what you need to do is mentally integrate the density of the veins found in the trenching program with the vertical nature of âboiling zonesâ. Favorable erosion levels are very important especially in mineral economics. If Mother Nature already removed most of what once was âoverburdenâ then thatâs a good thing from a mining point of view. Another phenomenon we need to evaluate is whether or not this deposit is a typical âepithermalâ deposit or more of a âmesothermalâ deposit. âEpithermalâ veins are near surface, they form at low temperatures and the individual veins are often fairly narrow. âMesothermalâ veins extend much deeper than âepithermalâ veins. They form at higher temperatures and they actually tend to widen with depth. There are some vein outcroppings on the southern downslope off of the plateau which suggest that the potential for these being mesothermal veins is still on the table but by no means a certainty.
What is striking to me is the POTENTIAL ECONOMICS at play here. There are no guarantees. Worldwide, the average âall-in sustaining costsâ (AISC) to produce an ounce of gold is about $907. The infrastructure present at the ADL, especially involving the access to power and water, is far superior to the average gold production facility. The ore we have is amenable to a 90%-plus recovery rate with simply gravity processes without the use of caustic chemicals. The ore present at the Don Luis Vein is unconsolidated enough to not even need blasting. I would assume that the cost to produce an ounce of gold here would be in the lowest quartile compared to other gold production facilities worldwide. The grades speak for themselves; they are insanely high at both the Don Luis 1 Vein and the Merlin 1 Vein/Caren Mine. Of these 5,000 meters of veins making it all of the way to the current surface, we know quite a bit about the grades present at the westernmost extent (the Caren Mine) and the easternmost extent (the Don Luis 1 Vein). The question is, can we assume that the grades in between the two are similar in nature. The vertical nature of âboiling zonesâ might suggest that we have a pretty good shot at it.
A recent update cited the plan to study the addition of an on-site ore crusher and a concentration plant. This would decrease the transportation charges on a per ounce produced basis since a highly concentrated ore could be shipped necessitating less truckloads for a given amount of production. The free-milling nature of the ore amenable to gravity concentration techniques and the lack of a need for blasting should uncomplicate the permitting process. Even at the meager 40 tonnes per day production rate anticipated for Q-1 of 2021 at just the Don Luis 1 Vein, with these grades this still represents gross production revenue of almost $1 million per week. Iâm assuming that high-grade production from the Caren Mine will come on line in the not-too-distant future. Production rates should also increase naturally through time and also as the Covid-related restrictions are alleviated.