An Existing Mineralised System
Having worked in the mineral resource industry for the last thirty years, I have seen and learnt a lot about the ins and outs of this industry. I remember asking an associate ten years ago why he knows so much about all the different projects. His answer was ... "Been there; Done that".
Once you have been in this industry for that length of time, you will begin to see the tress from the forest every time a new project comes to the surface.
Recently, I completed two Coffee with Samso with:
I have learnt a lot from my research when preparing for those Coffee with Samso. I have always known that the North American continent is awash with compelling and giant projects, but I have never paid much attention to the stories there. As they say, there is always something to learn and one never stops being hungry to gain knowledge.
In 2018, I had my first introduction to real gold projects from the United States. That was when an associate showed me a couple of projects in Montana. It was small scale but had great geology and potential. I was intrigued why and how this was still in the hands of a small cap company.
Over the years, I have heard much about how there were many great projects in the US that one could get one's hands on, but like everything else that is far away. These thoughts inevitably turn into a case of "out of sight, out of mind".
Figure 1: The Congress Mine lasted for decades and was the pride of Arizona (source: www.howtofindgoldnuggets.com)
The two projects were the US Grant and the Kearsarge gold projects that were held by Transatlantic Mining Corporation (TCO:TSX.V). These two projects are currently in the process of being sold to Endomines (Nasdaq Stockholm: ENDO and Nasdaq
Helsinki: ENDOM). From what I remember, the Kearsarge project was being promoted then as having the potential of over 500,000 ounces.
These two projects are evidence of good geological projects in the US. It is simply a matter of being active in this space and doing business in a foreign jurisdiction. I was told that it is easier to make these projects happen in the US than in Australia. I can attest to that thinking as when we were in New Zealand, it definitely was a lot easier while, perceptively, it was meant to be more difficult.
The photo above of the Congress Mine reminds me of the many old photos of mining towns in Australia. When I did some research on this topic, there were countless photos that depict old mining towns just like those in Australia.
Now, you would think that there would be many opportunities to create present-day mining provinces in the US. Not that there are none, it just feels that way for the non-initiated. We are talking about the likes of those that we see in Kalgoorlie, Murchison, Ballarat...etc.
Associates shared with me that the reason why you do not see the establishment of newer mining towns is due to their tenure system. Apparently, it is hard to freely consolidate large acreage.
There are still many opportunities in the US that are available to small companies and even individuals. You can imagine how my interest got piqued when I came across the projects that Riedel Resources Limited (ASX: RIE) and New World Resources Limited (ASX: NWC) announced.
Mineralised Zones - The place to find the action
As they say, the best place to find mineralisation is to go where all the cooking is happening. The subduction zones of the world are the main sources of mineralisation and all the biggest deposits are on these margins, or nearby anyway.
Figure 2: The world location of the major mineralised systems. Source: [1]
In Figure 2, you can see that the major mineralised regions are all placed in the margins of tectonic plates with big porphyry deposits. Some of the ones in China are not listed but I take it that is due to a lack of information, although they may not be classed as porphyry systems at the time of publication.
The reason why I like Figure 2 is that porphyry deposits are almost always the biggest style of deposits. They are the mega deposits and it is a good illustration as to the amount of endowment and the amount of "bubbling" that is required to create these deposits.
The thinking behind that is, the surrounding areas will also be accepted as "bubbling".
So when you take a step down from the world to a country scale, you start to see with more clarity, the concentration of mineral systems along the margin I mentioned in Figure 2. As we take note of the other world margins in Figure 2, it is easy to recognise the "cooking pot" that are in these regions.
It is not surprising that when you drill even further down to the project scale (Figure 4), you will see the density of workings, both big and small in these areas. As we all know, the mining of minerals has been happening this way before European migration into these regions.
Figure 3: A map showing the occurrences of significant mineral deposits in the United States. The is a clear preference to the subducting plate on the west coast of the Northern American continent. Source [2].
In terms of looking at the local prospectivity, you can imagine the density of prospects all along the western margin of the US (Figure 3 and Figure 4). You can now see how influential these plate margins are in creating mineralising sequences. Remember that these margins are continuously mobilising and creating multiple events of deposition and re-mineralising to create the myriad of deposit types over time periods of millions of years (Figure 4).
The La Caridad - Mineral Park Belt
The Kingman (RIE) and Antler (NWC) project both lie within the La Caridad - Mineral Park belt which is the dominant northwest trending structural zone. The belt runs for about 650km and is host to several porphyry, VMS and epithermal deposits. The structure is commonly interrupted by northeast-trending features and these spots seem to be coincident with the porphyry plutons [3]. These belts are deep rooted and the region has been exposed to numerous mineralisation events.
Figure 4: Map of the western United States cordillera showing ore deposits superimposed on major tectonic elements and Laramide igneous zones, sedimentary basins, and metamorphic belts. The western United States is divided into four generalised geologic provinces (boundaries shown as heavy solid and dashed lines): Pacific margin, Magmatic arc, Cordilleran fold and thrust belt and the Rocky Mountain foreland. The smallest and largest ore deposit symbols represent gross values of about $20 million and $60 billion, respectively. Intermediate sizes of symbols are based linearly on deposit gross values lying
between these extreme values. The short dashed line in northern Utah and southern Wyoming shows a segment of the boundary between the Archean basement on the north and Proterozoic basement on the south. It should be noted that although Jurassic accretion and magmatism resulted in complex geologic terranes along the Pacific coastal states, during the Laramide, these regions experienced downwarping and basin development. Specific deposits discussed in the text include: B = Butte and C = Cannivan Gulch deposits in Montana; T = Thompson Creek deposit in Idaho (Modified from Miller et al.,
1992).
As you can see in below (Figure 5), both projects sit in an apparent corridor with the Mineral Park (Cu-Mo) mine, Copperstone Mine and the Moss Mine (Au).
There are several smaller operations in the immediate area but these three major deposits will give a good flavour of what we are dealing with in terms of mineral prospectivity.
Let's look at the three deposits to get some idea of how rich this region is for metalliferous geology and why I like the projects owned by Riedel Resources Limited (RIE) and New World Resources Limited (NWC).
Figure 5: A map showing the two projects, the Kingman project and the Antler Copper project in the US that has been featured in recent episodes of Coffee with Samso in 2021. These two projects sit in a very mineralised system that has numerous events of deposition and are situated in a distinct structural corridor.
Moss Mine
source: [4]
The Moss mine is a heap leach operation which is owned by Northern Vertex Mining Corporation (TSX-V: NEE). The Moss Mine is a great example of what the local mineralising fluids are producing. It is a gold play that is using heap leach process to extract gold.
Geology of the Moss Mine
The host rock for the Moss deposit is the Moss porphyry, a uniform monzonite to quartz monzonite porphyry intrusion. It is coarse grained with 4 mm to 10 mm diameter plagioclase phenocrysts with biotite and lesser hornblende. There is also a fine-grained quartz monzonite porphyry, with 1 mm to 2 mm diameter plagioclase phenocrysts with minor biotite and minor magnetite, which is a later phase intrusive that cross-cuts the coarse porphyry and forms an intrusive breccia matrix in places.
The gold-silver mineralization is contained within three main veins and their associated stockworks: the dominant Moss Vein; a western extension of the Moss Vein (the “West Vein”); and the Ruth Vein to the south of the Moss Vein. Moss Mine Project drillhole logs and assay database indicate a potential for other mineralized veins that are both similar to and sub-parallel to the Ruth Vein. For purposes of geological domaining they have been termed Vein No. 4.
The Moss mineralization is unique in comparison to many other epithermal deposits subject to heap leaching because, within the depths being exploited for mine operations, as they do not exhibit the traditional oxide-transition-sulphide boundaries. The sulphide zone is well below the maximum depth of mining. The primary mineralization consists of free gold in quartz and calcite veins.
Resources of the Moss Mine
Table 1: The Mineral Resources Estimate for the Moss Mine, Arizona. Source [4]
According to the Northern Vertex website,
"The Moss Mine is an open pit gold-silver operation, with a favourable strip ratio of approximately 1.85:1 (waste to ore) and minimal haul distances to the crushing plant. The most economic and effective way to process the ore is through crushing, agglomeration and heap leaching followed by processing at the on-site Merrill Crowe metal recovery plant and refinery to produce gold and silver doré bars. According to the Company's Feasibility Study (2015), throughput at the Moss Mine was expected to be 5,000 tonnes per day (tpd), however since commissioning was announced in 2018, throughput has been significantly higher due to exceptional performance of the crushing plant and operational team, which set a one-day throughput record of 13,000 tonnes. "
Copperstone Mine
The high-grade Copperstone Gold Mine is located in LaPaz County, in western Arizona, in the United States. It is within the Walker Lane mineral belt where it intersects gold provinces in Southern California and Western Arizona. Arizona Gold Corp. (TSX: AZG ; OTCQB: AGAUF) acquired the Copperstone gold mine located in Arizona in 2014. The mine is fully permitted with significant mining infrastructure, mineral resources and processing infrastructure in place.
Between 1987 and 1993, the Copperstone mine produced up to 500,000 ounces of gold.
Geology of the Copperstone Mine
According to the website of Arizona Gold Corp, gold mineralization at Copperstone occurs principally within the moderate to low-angle Copperstone Fault which has been interpreted to be a listric fault associated with the underlying Moon Mountain detachment fault. Gold occurs as native flakes within fault breccia, gouge and shear zones related to the faulting.
The wall and host rocks are typically Triassic sediments and Jurassic quartz latite volcanics. Gold is commonly associated with hematite, chlorite, quartz, manganese oxide and copper oxide mineralization. In the case of the Copperstone Mine, the gold is not encapsulated in sulphides or silica, and the ores do not contain active carbon.
This means that the ores at Copperstone are not refractory. This is a consequence of the fact that these ores appear to be comprised of “original”, or “primary”, or “hypogene” oxides minerals.
Figure 6: At the bottom of the Copperstone pit. (Source [8])
Mineral Park
The Mineral Park orebody is associated with a complex of late Tertiary monzonitic rocks within two main stocks intruding Middle Proterozoic lithologies (Figure 6). Economic Cu mineralisation is only present within the supergene blanket, with hypogene grades of 0.1 to 0.15% Cu and 0.04% Mo. The deposit is located within north-western Arizona, about 125 km to the north-west of Bagdad and lies within the Arizona-New Mexico Basin and Range Province. [5]
According to [6], the now delisted owner of Mineral Park, Mercator Minerals (TSX: ML; US-OTC: MLKKF), released an estimate of the reserves at Mineral Park in July 2013.
The new estimate pegs reserves at 369 million tons (335 million tonnes) grading 0.12% copper, 0.037% moly and 0.08 oz. silver per ton. This replaces the previous estimate of 389 million tons (353 million tonnes) of 0.138% copper, 0.04% moly and 0.08 oz. silver. Tonnage has dropped by 5%, and copper and moly grades have slid by 13% and 8%.
The latest reserve contains 876 million lb. copper, 273 million lb. moly and 31 million oz. silver. Another 72 million lb. copper will be recovered through leaching. This compares to the previous estimate of 1 billion lb. copper, 310 million lb. moly and 31 million oz. silver, plus another 86 million lb. copper estimated to be recovered from leach ore, notes Laurentian Bank Securities’ analyst Christopher Chang.
Figure 6: Mineral Park mine from the air, 2008. [7]
Large scale copper mining began in the old Mineral Park district in 1963 when Duval Corporation began the open pit operation. The mine changed hands and owners several times and was acquired by Mercator Mineral Park Holdings of British Columbia in 2003. In December 2014 the mine closed as the company filed for bankruptcy.[7] On January 20, 2015, it was reported that Origin Mining Company, a subsidiary of the Canadian company Waterton Global Resources who also own Elko Mining Group and Carlin Resources LLC in Nevada, had purchased the property. [7]
What Does Mineralisation Mean For The Average Investor?
On the 18th May 2021, Northern Vertex Mining Corporation (TSX-V: NEE) announced a drilling intercept of 28.96m at 2.28g/t Au and 28.84 g/t pf Ag which was part of the near mine exploration. This included the following,
9.15 meters grading 4.90 g/t Au and 57.18 g/t Ag for the Moss vein in drillhole AR20-359R
4.6 meters grading 4.01 g/t Au and 27.97 g/t Ag for the Ruth Vein in drillhole AR20-364R
Drilling indicates consistent intersections of elevated gold and silver mineralization along more than 500 meters of the Ruth Vein, approximately 100 meters south of the crest of the Moss Center pit.
In March 2021, Riedel Resoruces Limited announced the following results,
3.8m @ 98.9 g/t gold & 151 g/t silver from 20.6m including - 1.5m @ 230.8 g/t gold and 359g/t silver from 20.6m
1.5m @ 15.56 g/t gold & 29 g/t silver from 28.2m
4.6m @ 4.44 g/t gold & 7.8 g/t silver from 18.3m including - 2.3m @ 7.62 g/t gold & 12 g/t silver from 18.3m
4.6m @ 4.24 g/t gold from 10.7m and 2.3m @ 2.82 g/t from 29m
1.5m @ 11.46 g/t gold & 35 g/t silver from 20.6m
1.5m @ 39.3 g/t gold & 323 g/t silver from 37.3m
18.3m @ 2.22 g/t gold & 11g/t silver from 100.6m including - 4.6m @ 8.39 g/t gold & 39 g/t silver from 100.6m
Figure 7: A schematic cross-section of the first drilling program by Riedel Resources Limited at the Tintic prospect.
The results that Riedel announced in March 2021 have some consistency with those that were observed by Northern Vertex. As we all know, it is not appropriate to compare apples with oranges, but when you consider the potential spatial relationship the two projects have in terms of the structural corridor, you would have to consider this as a positive resemblance.
When you look at the gold grades that were discovered at Tintic (Figure 7) and Merrimac (Figure 8), the first thing that came to my thoughts is that the fluids must be rich and the source must be able to sustain this kind of numbers. Scientifically, one cannot believe that this is a freak of random occurrence as the surrounding area appears to be carrying numbers too.
Figure 8: A schematic cross-section of the first drilling program by Riedel Resources Limited at the Merrimac prospect. [10]
What is of more interest to me is their second drilling program as they uncovered a couple of mineralised bodies (Figure 10). The first intercept was literally from the surface and the other around the 40m down the drill hole. The gold grade was not spectacular but the combination was VERY interesting. This program showed that the mineralised strike that Riedel has is prime for gold, silver, zinc, lead.... Smelling like a VMS to me :-) or a variation of something more exotic. The mix of metals is very interesting and as an every optimistic exploration geologist, I am smelling something more than a quartz vein with some gold.
This second program triggered a lot of selling on the Riedel share price which was bizarre (Figure 9). To me, this was a fantastic result, you have just confirmed mineralisation further along strike. The results also boast confidence that your mineralisation is more widespread. In addition, the mixture of metals tells you that you have a very fertilised source and it is mineralising within your tenement boundary.
Figure 9: Price chart for RIE. Source: [www.commsec.com.au]
Another point is that the mineralisation is shallow, very shallow. A first up drilling program revealing consistent mineralisation but the market sold it down. The negative sentiment from the market tells me that there is a disconnect between what is in the ground and what the market understands is in play.
I feel that the market is not appreciating the discovery and confirmation of mineralisation along strike. To get that kind of results on a first up drilling program has been misinterpreted as a failure. Hence, if investors see some merit with my interpretation of events, this may have brought a good entry value for new investors or those that have felt that they missed out previously.
With a current market capitalisation of AUD18.51M (26th May 2021), thanks to the sell down, it makes an interesting value proposition.
Figure 10: The Jims prospect drilling result. [10]
Excellent results returned from the recently discovered “South Shoot”, including:
17.1m @ 3.3% Cu, 9.5% Zn, 1.2% Pb, 34.8g/t Ag and 0.16g/t Au from 396.2m
(17.1m @ 5.5% Cu-equivalent*) in ANT56 – the deepest hole drilled to date in the
South Shoot; and
11.1m @ 4.4% Cu, 9.7% Zn, 0.5% Pb, 29.6g/t Ag and 0.26g/t Au from 289.9m
(11.1m @ 6.4% Cu-equivalent*) in ANT47 – approximately 250m up-dip from ANT56.
Impressive results also returned from the “Main Shoot”, including a total of 19.3m of
mineralisation in the deepest hole New World has drilled to date, comprising:
14.3m @ 2.3% Cu, 6.8% Zn, 0.3% Pb, 22.4g/t Ag and 0.28g/t Au from 614.0m
(14.3m @ 3.8% Cu-equivalent*) and
5.0m @ 2.2% Cu, 2.9% Zn, 0.1% Pb, 10.8g/t Ag and 0.27g/t Au from 639.3m
(5.0m @ 2.7% Cu-equivalent*) in ANT53
Figure 11: . Long Section through the Antler Deposit showing the location of the Company’s drill holes (gold and green colours), with historical underground workings, historical drilling and select significant intersections in previous drilling (white text boxes). [9]
When you add the results that New World announced to the mix of drilling results from Kingman and Moss, I cannot help but agree that this corridor, that previous authors have highlighted, is consistent to mineral mineralisation. There is no doubt in my mind that this corridor is abundantly mineralised.
In their presentations and in the Coffee with Samso, Riedel and New World Resources talk about a long strike length of mineralisation and readers should look at that with more interest.
Readers should keep thinking about the fluid action that is creating all the nice numbers. When you look at Figure 11, you should be able to get a good sense of what I am talking about. This long section view is one of the best methods of visualising how the potential ore body is plunging/dipping.
So What Does All This Mean?
If you look back at Figure 2, you would notice that Tintic was named and it was classified to have Ag, Pb, Zn and Cu. The drilling results that Riedel announced indicate similar metals being analysed. So if you deduce this as having similar source magma, then this should be expected.
Tintic is along strike from Jim's (Figure 12) and there seems to be a "cluster" of mineralisation. Merrimac, which was part of the first drilling program, some high grade gold numbers too.
So you have Antler which is an obvious VMS to the south, Tintic which has been classified as VMS-type at the very least and Jim's showing some VMS properties, the pieces seem to point to similar types of potential deposits.
As we are moving up the perspective view (Figure 12), you will see the major copper mines (porphyry related) to the south and the potential of creating of clusters around the Kingman, Antler and Mineral Park region.
I do realise that there is a fair bit of postulating happening here but from an exploration point of view, I cannot help but see the northwest corridor happening in the same way. I would say that if you looked at the local geology around each of those red dots to the south, you would most likely see similar things to Kingman and Antler.
Figure 12: The spatial relationship between the Kingman and the Antler project.
Conclusion
I hope I have painted a good enough story to show the reasons why I think the La Caridad - Mineral Park Belt is a cooking pot for metal deposits. The presence of porphyry systems along this structural corridor which is obviously deeply sourced is the perfect machine to create numerous deposits stretching the whole 650km.
It is no coincidence that in every part of the world where these tectonic margins exist, you get a lot of metals being precipitated out of the magma. The numerous porphyries being documented in the southern part of the La Caridad - Mineral Park belt is clear evidence of a fertilised system.
The biggest issue for both companies is to keep finding money because they need the flow of funds to keep up with drilling. What I am confident is that they do not have to worry about finding mineralisation.
References
[1] - Sillitoe, R.H. 2010 Porphyry Copper Systems - Economic Geology V105, pp 3-41
[2] - Long, Keith R., DeYoung Jr, John H., Ludington Steve. 2000, Significant Deposits of Gold, Silver, Copper, lead, and Zinc in the United States, Economic Geology, Vol. 95, pp 629-644.
[3] Hildenbrand T.G., Berger Byron, Jachens R.C., and Ludington Steve, 2000, Regional Crustal Structures and Their Relationship to the Distribution of Ore Deposits in the Western United States, Based on Magnetic and Gravity Data, Economic Geology, Vol. 95, pp 1583-1603.
[7] Wikipedia
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