a Cigarra – a unique low sulfidation epithermal deposit
Vimca99, I am not a geologist. I am just an average investor. I have a strong analytical background. I guess people with those skills tend to apply the same analytical approach to all aspects of life. Plus, I like to learn about subject matters that helps me to better visualize things, especially when it comes to mineral deposits and how it relates to my investments. La Cigarra appears to be a very unique deposit, with perhaps no known exact comparisons. Some background info on La Cigarra. From the technical report (pg. 1-9): ``Interpretations: Geologic understanding of the deposit as a low sulphidation epithermal and subsequent wirefame interpretations appear sound and the exploration plan going forward is to target adjacent peripheral areas with similar alteration characteristics as the known mineralization in the San Gregorio-Las Carolinas area.`` From pg 8-1: ``Deposit Types: The La Cigarra deposit is an unusual, disseminated, sedimentary hosted, structurally controlled and low to moderate sulphidation, epithermal silver deposit that is concordant with bedding and has no known analogues. It is characterized by the high aspect ratio of the mineralized system in which similar styles and grades of silver mineralization persist for over 3km of length and widths of less than 80m along a north to northwest striking fault zone. It is likely the faults act as the plumbing system for the fluids that alter stratigraphy and bring in the siliceous, silver-bearing fluids.`` Also from pg 8-1: ``Although epithermal deposits often have a clear magmatic source that drives the hydrothermal system, the only suggestion of an underlying magmatic body at La Cigarra is provided indirectly by the strong magnetic anomaly identified below the San Gregorio and Las Carolinas zones. However, many rhyolitic sills and occasional dykes that occur throughout the San Gregorio and Las Carolinas zones contain 1-2mm wide drusy quartz veins with significant silver values. These intrusions are associated with increased silver values in the surrounding sediments and its thought a particular phase of the rhyolitic sills were associated with the silver-bearing hydrothermal fluids that created the La Cigarra deposit. Lastly, the uniqueness of La Cigarra is that it is essentially a true silver deposit with a Ag:Au ratio of about 1200:1. It also contains low lead and zinc values (approximately 1:1 ratio) and very low copper values.`` There is a lot of good info in there about La Cigarra. I will probably highlight a couple of points. Before I do that, it will probably help if I provide a brief high level background on sulfidation (sulphidation) structures. The earth`s crust is broken into many moving tectonic plants. The intense bumping of the plates is what causes earthquakes and volcanoes. A mineralized sulfidation environment likely needs a nearby volcanic heat source to exist. Mexico is positioned well for these kinds of structures. Here is a diagram of tectonic plate locations in the pacific area, with major active volcanoes highlighted in red and yellow: https://www.bobnholli.com/Sequim/WashingtonState/PacificMountainSystem_files/PlateTectonics_files/CircumPacificEQ_files/CircumPacificEQ.htm As a side note, Marianas Trench can be seen (about 100-200 miles from Guam, not too far from Japan). Marinas Trench is the deepest area on the surface of earth (7 miles, caused by intense subduction from the tectonic plates). Typically, low sulfidation formations are responsible for epithermal deposits (including bulkier ones like La Cigarra) while high sulfidation formations drive the high grade narrow vein type deposits. I think the primary difference might be that low sulfidation fluids interact with a lot of water when moving up to the surface (thus the mineral content gets spread out, and the mineralized body becomes wider, but with lower grades) while the high sulfidation content likely interacts less with water thus minerals remain more intact (with narrow widths) while shooting up to the surface. Variations in temperature probably has an influence also. An environment with both low and high sulfidation styles could also host a porphyry structure at depth. Here is a diagram of what this type of environment could typically look like: https://www.unalmed.edu.co/rrodriguez/Ore-Genesis-Notes/Epithermal%20Au-Ag_archivos/img002s.gif As you can see on the lift side of the diagram, there is a hot spring that housed the epithermal fluids, in this example. Perhaps the hot spring might be considered one of the feeder zones in this example. Perhaps the hot spring distributes mineralized fluids to adjacent areas then eventually dried up. In such a case the dried up hot spring could have remaining bonanza like material imbetted within the rocks/soil, as a dried up feeder zone. I suppose the porphyry area at depth could be considered the original feeder zone also. Getting back La Cigarra, they haven`t discovered a feeder zone as yet. It could be an interesting development if a feeder zone eventually gets discovered on the property. It`s likely that the faults act as the plumbing system to enable the mineralized fluids to travel along the 6.5 km La Cigarra body. My guess is that if there is a feeder zone near the surface then it might be located somewhere below the primary surface layer of mineralization at the San Gregorio zone. I think it`s good that Northair has a large property package in the general Parral area because you have to wonder if there is a relationship between various known deposits. For example, I have read elsewhere that San Francisco Del Oro (now controlled by Minera Frisco, 531 million silver ounces of past production & resource) is an epithermal deposit – located just 20 km south of La Cigarra. Then you have Veta Colorada (owned by Silver Standard, 249 million ounces of past silver production & resource) located just 20 km southeast of La Cigarra. Veta Colorada is likely a high sulfidation structure (high grade, narrow veins). The close proximity of all of these major deposits have to leave you to wondering if they all originate from the same volcanic area at depth (a similar set up to the diagram), with some silver coming to the surface as low epithermal sulfidation deposits and some as high narrow sulfidation deposits. I guess it`s impossible to know at this time, but just in case, its good that Northair controls such a large property position in the area. You never know what else has bubbled to the surface in the area, just waiting to be discovered. There are already some good very early signs that Northair`s La Bandera zone could turn out to be a La Cigarra like structure (located 5 km to the north).