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  • sfsi_mont sfsi_mont Oct 7, 2013 2:13 PM Flag

    . .Mineralization and Rare Earth Elements in Nevada

    The article below is very long and was written by what appears to be a Geologist.
    Grant it, it was on a different message board with a different Company involved.
    but non the less, this is what's under the earth in Nevada. Perhaps Matthew needs to see this.

    Nevada's unique and profitable Carlin antimony-gold hydrothermal deposits:
    Antimony has been found in a few places such as China and Bolivia, but no new deposits have been developed in over ten years, and China may no longer continue to export its antimony. But even if it did, geologists think that there is now a much more lucrative area of the world for antimony mining; the Carlin sediment hosted hydrothermal antimony-gold deposits of Nevada . Many geologists have observed the association of antimony and related metals with Nevada's Carlin gold hydrothermal deposits and this association is what can make the deposits so valuable.

    To understand this, geologists state that you need to consider how these unique deposits were formed in Nevada and nowhere else in the world. Starting about 220 million years ago and lasting for 175 million years, there were three episodes where molten magma rose upwards towards the earths crust in Nevada.

    Magma forms in the upper part of the mantle. The mantle is the planet’s middle layer, a buffer of molten rock and metal between the rocky crust – the top 5 miles or so of the earth – and the core which is composed of the heavier metals which sink downward because of their weight and density. The mantle is a slow rolling mass of rising and falling material. It picks up the deeper heavy molten metals and its slow but constant convection brings them from deep within the planet to near the surface.

    Even though magma contains metals, they are thinly diffused and would not be economical to mine even if the magma reached the surface. However, as the magma nears the crust, whose rocks have a high sulfur content, the sulfur melts and mixes with the magma. Sulfur is a very reactive chemical and as it circulates in the magma it absorbs metals and over this very long time period of 175 million years, it concentrated them by a factor of over a 1,000. There were three episodes where magma interacted with the crust and had its metals scavenged by sulfur. The first two magmas contained gold, antimony, mercury, tungsten, thallium, tellurium and silver. The third magma intrusion contained molybdenum, lead, vanadium and zinc.

    All three of these magma layers were about 40 kilometers deep, too deep to readily interact with the earth's crust, but 42 million years ago and lasting until 36 million years ago, a period of 6 million years, there was an upwelling of the magma that brought it to within 4 kilometers of the earths surface. This upwelling fractured the earth's crust over Nevada and formed multiple deep cracks and fissures along fault lines which allowed surface water to work its way down to the magma. This surface water contained carbon dioxide which formed carbonic acid, plus as the water encountered the sulfur in the magma, it formed a hydrogen bisulfide complex. Gold was transported mainly as a bisulfide complex Au(HS)2- antimony and the other metals reacted with the carbonic acid and under the high temperatures and pressures were transported as chemical complexes, for example antimony was transported as a H3SbO3 complex.

    Most metal deposits in the world are derived from hydrothermal systems where superheated water under great pressures, circulating kilometers deep in the crust, dissolves the metals it encounters and then as the heat expands the water, it moves upward and deposits the metals in fissures and faults near the surface forming veins of metal. Typically, such a system would remain active for hundreds of thousands of years to as much as perhaps a couple of million years. In Nevada this hydrothermal system stayed active for 6 million years and so much larger quantities of metals were carried upward than normally occurs.

    These deposits cover large areas and can extend to great depths. The only gold system that is larger than Nevada's Carlin trend, is the one in South Africa. More gold has been mined from Carlin-type deposits in Nevada in the last 50 years than was ever mined during the California gold rush of the 1800s.

    As stated above, usually gold and other metals contained in the ascending hot acidic hydrothermal fluids are deposited in cracks and fissures near the surface where falling temperature and pressure and neutralization of the acid by carbonate rocks causes the metals to precipitate out of solution. In Nevada, however, the rock formation is very porous and so the water did not have to follow the cracks in the rock to work its way upward, it just made its way upward through the permeable rock formation. In addition to that, the rock formation is filled with tiny microscopic specks of iron. Iron has a higher affinity for sulfur than gold and so it would react with the sulfur in the water and form pyrite, iron sulfide. Since the sulfur was no longer available to keep the gold in solution, it would precipitate out and be incorporated with the pyrite.

    This is why gold in the Carlin trend deposits occurs as submicron particles (50–200Å) primarily within the lattices of pyrite. The deposits are large in size because the gold formed in a large porous formation. But even though the gold particles are too small to be seen by the naked eye, their quantity is huge. The deeper portions of the Carlin deposits contain 7 -10 grams of gold per ton, which is very high grade, while the portions closer to the surface contain 1-5 grams/ton, which is still considered good to excellent.

    At the depths where the gold precipitated out, the hydrothermal fluid was still over 200 degrees Centigrade and still at great pressure, so the other metals stayed in solution and were carried closer to the surface. The water continued to cool as it moved upward and when it encountered cracks near the surface, the sudden drop in pressure would cause these other metals to precipitate out of the solution and form veins of metal.

    The metals that would be present in the solution would depend on which magma layer it had circulated through and on its salinity. High saline water, brine, more readily dissolves molybdenum and vanadium. That is why different areas can have different mineral deposits. Most of the deposits would have ended up underground, but over time, erosion exposed many of these deposits.

    Since the hydrothermal waters circulated through the molten magmas for 6 million years they must have also scavenged large amounts of the other metals such as antimony and tungsten along with the gold and formed large and multiple deposits of these metals, although the deposits would have been above the gold since it precipitated out first.

    That large amounts of the metals in the magma that were present with the gold were also transported upward and deposited at the surface is indicated by the number of mines in Nevada, many of them in Pershing county, where Fencemaker is located. In Pershing county there have been 100 antimony mines (usually also containing some of the other metals such as mercury, tungsten and silver etc.) 127 tungsten mines, 50 mercury mines, 34 molybdenum and even 6 vanadium mines. We will probably not be mining any vanadium by our Fencemaker site, but we do have our San Juan uranium-vanadium property and so it is interesting to note that vanadium has now also been declared a critical metal.

    Because of the way the metals were deposited, near surface deposits, such as antimony, may also contain mercury and silver and even some gold or other minerals. And further down it might also contain tungsten which tends to precipitate out of solution before the other metals. When Fencemaker was owned by Walter Gentz and Jonny Vogel its production, in addition to antimony, included mercury, silver and gold. If any more mercury is found in our Fencemaker mine it could be very profitable. The price of mercury varies depending on its purity, so a better way to price it is by the cost of its ore, cinnabar, which is 86% mercury. Cinnabar sells for $75 a pound.

    Many geologists now say that in Nevada, if you locate an antimony deposit which is located in the porous formations where Carlin gold deposits can form, it could be classified as a leakage deposit and it may mean that there is a deeper, very profitable, Carlin gold deposit below the antimony deposit . Fencemaker is located in just such a formation so it will be interesting to see what the company finds if it does any deep drilling. In addition to this you should also check to see if the other metals such as silver, mercury or even tungsten (another critical listed metal) might be present. Even though most of the gold was probably deposited in deeper sites, some might be present.

    Usually gold is produced by using a leaching solution of cyanide, but the occurrence of antimony interferes with the process and hinders the leaching effect of cyanide on the gold ores. Therefore, many antimony bearing gold deposits have in the past had low overall recoveries for the gold and the antimony. However, the efficiency of extraction processes for auro-stibnite ores has advanced significantly over the last 20 years as a result of a better understanding of the properties of antimony, and modern process designs incorporating flotation of antimony prior to CIP treatment of float tails now result in very good recovery rates for both gold and antimony.

    The magma that created these deposits also contained thallium and tellurium. Thallium is being researched for the development of high-temperature superconducting materials. The applications being considered are magnetic resonance imaging, magnetic propulsion, and electric power generation.

    High-temperature superconductors (HTS) enable electric power to be carried over long distances with minimal loss. A single HTS cable can replace an entire transmission line carrying power from the generating source to final destination.

    Thermoelectric materials transform heat into electricity and vice versa. The number of applications is vast. Many components, ranging from vehicle engines to computer chips, give off heat, wasting part of the energy generated. Thermoelectric materials have the capability to transform this heat into usable electricity, which opens new prospects. Furthermore, new appliances become possible, such as refrigerators with no moving parts.

    The price of thallium has been climbing over the years because it is becoming increasingly in demand for its unique properties in specialty applications and its price is now $250/lb. Several thallium minerals, containing 16% to 60% thallium, occur in nature as complexes with antimony.

    Tellurium also has many uses and its price is $100/lb. But even though thallium and tellurium are rare metals and expensive, most people have not heard of them, and that includes miners, so very few companies tested their sites for these metals.

    There was only one mine historically that produced thallium in Pershing county and that was the Relief Canyon Mine which produced thallium, antimony and mercury. There was also only one mine that produced tellurium, and that was the Plainview Mine which produced tellurium, and gold. Tellurium combines with gold to form two ores, krennerite and calaverite, it also combines with antimony. Concentration increases with depth.

    Thallium minerals, are all rare and expensive, and have been found in only a few localities, such as Lengenbach, Switzerland and the Hautes-Alpes of France; but now they have been found in sediment-hosted gold deposits in the U.S. Southwest (e.g., Carlin, Nevada) including two new thallium minerals, Weissbergite (Thallium-Antimony compound) found in the Carlin Gold mine, Elko, and Christite (Thallium-Mercury compound) also found in the Carlin mine. Lorandite, A thallium sulfosalt mineral, has been found in other Carlin gold deposits. So there is no reason to believe that thallium ores should not be found in other areas or mines in Nevada.

    Tellurium and thallium minerals, although widely disseminated, do not form ore bodies, they are always associated with related ores such as antimony and gold. Hence, there are no deposits that can be mined for tellurium or thallium alone, and there are no formally stated reserves. Mining companies have historically not checked for the presence of these metals, but with their increasing importance, any gold or antimony deposits should be checked for these metals, especially Carlin-gold deposits.

    And now we come to an interesting and even exciting potentially profitable situation. A group of highly sought, critical metals, that previously have not been associated with Nevada: Rare Earth Metals (also called Rare Earth Elements: REE).

    There is only one company in America producing rare earth metals, although only the lighter less valuable rare earth metals, and that is Molycorp’s California Mountain Pass mine which is located just miles from the Nevada border. The rare earth metals originated in a 2 billion year old volcanic layer that lies under that part of California, and which it turns out, also projects into Nevada. So Elissa Corporation staked out an area in Nevada next to the California border and has found deposits of the heavy rare earth metals deemed to be most critically short in supply – dysprosium, terbium, yttrium and neodymium, which is very interesting because it indicates that the volcanic layer becomes more highly enriched with the valuable heavy rare earth metals as it extends into Nevada.

    At this time it is not known how far this volcanic layer extends into Nevada. The Geologic department of polytechnic university states that no systematic study has been undertaken, and little appears in publication, regarding the rare earth mineralization of Nevada, although a study years ago by the US Geologic department did show that rare earth metals were present through out Nevada, but not the amounts.

    So we know rare earth metals are present in Nevada. In fact, in addition to the rare earth metals found next to the California border, rare earth metals have been found in the Ordovician Vinini Formation type-section in central Nevada.

    The Nevada geologic society states that old mines were almost never analyzed for anything other than the target mineral and that abandoned mines could contain rare earth metals.

    An 1870 sample collected from a failed copper mine was found to be high in Indium, a metal used in solar panels. It's this discovery that led the scientists to believe that abandoned mines could contain rare earths. Mine tailings from abandoned mines are now being tested for various rare earth metals. The resulting search has already thrown up some surprises: rare earths were found alongside minerals that were not known to occur together.

    A bill, (H.R. 6160), would authorize the US Department of Energy to guarantee loans to US companies that want to mine rare earths but lack the technologies that are needed both to separate the desired elements from the chemically similar ores and to reduce the separated oxides to metals.

    Pershing County, Nevada holds much promise for discovering new mineral deposits. The Pershing Gold and Silver Trend is under-explored compared to other northern Nevada gold districts. For decades, most of the exploration conducted in northern Nevada has focused mainly on gold districts like the Carlin Trend and the Getchell Trend which are located east of Pershing County. In addition to that, the area is full of abandoned mines that were not tested using modern technologies and so they could still contain valuable amounts of ore, especially since the amount of metal that was deposited is probably larger than previously expected. Plus when they were mined they were not tested for minerals other than their targeted metals. The sites I researched say that the old mining sites should be tested and if a previous mine is re-opened, since we now know the geology that formed the deposits, it might be worthwhile to test for the various metal ores, including the rare earths, plus check for deeper deposits of metals, including Carlin gold deposits. All in all, our Fencemaker mine could be even more valuable than we thought.

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