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Aurcana Corporation Message Board

  • tranthor2004 tranthor2004 Jun 6, 2012 3:36 PM Flag

    Block 3/Gold exploration in Presidio Co.

    Looking at table 1.5 of the feasibility showed a M & I of 196K tons 4 oz cutoff grade in block 3.

    Recent drill report good, obviously.

    From same report:

    .30 oz of gold would be nice. :-)

    The Gleim Property, south of the Presidio mine, has the potential for structural-related silver and gold mineralization. GFMC drill hole SD 264 encountered 7 feet of 10 ounces silver per ton, 0.07 ounces gold per ton, 4 percent lead and 2 percent zinc at 393 feet. Drilling is needed to determine the width and length of this portion of the structure. Samples containing high gold values were reported taken at the east edge of the Gleim Property.

    Shafter Silver Project Aurcana Corporation
    lead-zinc veins (often with some minor gold values) with past production at the Montezuma, Chinati, Perry, Gleirn and MacDaniel workings.
    GFMC never followed up on a large zone of bedded and oxidized zinc mineralization that they discovered during their regional drill program. The north-south drill fence with SD 313, SD 316, and SD 317 intersected 6 feet of 10 percent zinc mineralization extending 1,200 feet down-dip from the Montezuma workings. Drill hole SD 313, located approximately 200 feet south of the old mine, encountered two 6-foot zones with 14 percent zinc and the bottom horizon contained 0.03 ounces gold per ton. A 4 percent to 6 percent zinc zone was also encountered in GFMC’s drill holes along strike in fences 2,000 feet to the east and 3,000 feet to the west from the Montezuma workings. The zinc mineral is described as smithsonite. Metallurgical test work is reported to be able to recover this oxidized mineralization.
    The last 30 years of exploration has encountered numerous gold intercepts of merit, but no follow-up work was undertaken. For instance, GFMC drill hole SD 301 encountered 6 feet at 0.52 ounces gold per ton mineralization at 943 feet near the top of the Permian Mina Grande formation (the main ore-bearing sedimentary horizon for the district). SD 301 was not offset with additional drilling.
    On both the east and west sides of the Red Hills intrusive, detailed chip sampling of mineralized outcrops of the Permian sediments was done by Duval and outlined significant zones of gold and silver anomalies. Twenty-eight sets of samples were taken and 18 of these sets had gold values that ranged from 0.005 ounces per ton to 0.33 ounces per ton. Silver values in 6 samples ranged from 2 to 21.2 ounces silver per ton. The mineralization is generally just below the Permian/Cretaceous contact and often associated with igneous sills and southwest-northeast structures.
    On both sides of the draw hosting the MacDaniel underground workings, drifts have been worked on strong structural mineralization. Sampling by RGMC on the north-dipping N75°W structure indicated plus 6 feet carrying 0.03 ounces gold per ton, 1.2 percent lead, and 13.2 percent zinc at the surface. These workings were driven prior to World War II, when gold was $30 per ounce and zinc was $0.12 per pound.
    Northwest trending structures at the MacDaniel workings and at the Sullivan Mine to the west of Shafter demonstrate values of up to 0.30 ounces gold per ton, 2 to 6 ounces silver per ton, 4 to 20 percent lead, and 3 to 10 percent zinc.

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    • While Aurcana is opportunisticly picking some low hanging fruit so to speak ( open pit mines ) it gives them more time to explore the rest of the property to cherry pick the best sources of mineral ores.

      La Negra is a perfect example or a mine and mill that can blend different materials to produce a number of metals at the same time. La Negra's lead and zinc production doubles up the silver revenue. If Shafter can get to that point then silver revenues could be doubled up with Gold, lead and zinc production if feasable.

      • 1 Reply to rholl49oswego
      • <<<While Aurcana is opportunisticly picking some low hanging fruit so to speak ( open pit mines ) it gives them more time to explore the rest of the property to cherry pick the best sources of mineral ores.

        If Shafter can get to that point then silver revenues could be doubled up with Gold, lead and zinc production if feasable.>>>

        Per feasibility:

        Internal opportunities include:
        1. Decreased operating costs
        2. Decreased construction costs
        3. Increased run-of-mine head-grade (this is likely as a bulk sample from Block 1 had a
        10% to 15% higher metal content than reported by borehole assays, probably due to ore
        preferentially washing out of borehole core material during drilling)
        4. Increased rate of production of run-of-mine ore
        5. Decreased dilution of run-of-mine ore
        *6. Increased metallurgical recovery Increasing the Mineral Resource by extending the limits
        of the orebody by exploration drilling / development, and by filling gaps in the known
        orebody information by delineation drilling*
        7. Conversion of Inferred Mineral Resources to Measured or Indicated by infill drilling
        8. Discovery of additional Mineral Resources
        *9. Recovery of gold, lead, and zinc from the ore*

        Met testing showed variability in recovery rates up to 92%. Potential is there to raise the 84% recovery. Ching.

        We have no idea of the amount of zinc and lead byproduct at this time. The drilling was mostly done a long time ago by Silver Standard and/or Gold Fields.

        I hope they are in the process of buying property "in trend" to the west.

    • The Tasco website and their property report described the Shafter District.

      One of the pieces of information mentioned the Presideos "open pit" operation as having 3 million oz of silver. That was from the owner in 1998 (I forget the name)

    • Here is the write up on page 21 of the district history as written up by Tasco.

      Most of the production of the mines in the Shafter district was of lead, zinc, and silver; the Presidio mine
      was the area’s only large mine. The Presidio produced two million tons of silver-lead-zinc ore from
      1880 to 1943 (Peterson, 1973); reportedly the mine yielded 35.92 million ounces of silver at an average
      grade of 15.4oz Ag/ton, of which about 84% of the silver (30.29 million ounces) was recovered after
      processing in the local Shafter mill (Rio Grande Mining Co., 1998a). Gold Fields identified a silver
      “resource” at the Shafter silver deposit adjacent to the Presidio mine of 29.68 million ounces of silver
      with a grade of 7.6oz Ag/ton at a cutoff of 3oz Ag/ton
      plus a “potential open-pit resource” of about 3 million ounces of silver averaging about 6oz Ag/ton (Rio Grande Mining Co., 1998a).

    • Rholl,

      Thanks for that info. Good stuff.

      I am a little confused about the open pit mining scenario.

      From the feasibility 1.4.2 - <<<An 18 month mine development schedule is envisaged, which will allow full production of ore from Blocks 2 and 3 by the time the process plant is commissioned. 50,000 tons of ore will be produced during this mine development and pre-production period, which will be stockpiled on surface adjacent to the process plant.>>>

      The open pit was not in the study so does this mean ore was still stockpiled in your opinion or deferred for the open pit?

      I was looking for for a 3D underground ore body, mining, drill holes, etc. but have not found one. I did find the SSRI study done by PAH:

      Much of it was incorporated in the Aurcana Feasibility but Figure 4.2 page 19 provides a alternate property owner map.

      I also found mention during core drilling of a "nugget effect". This could mean higher Ag content in the ore than cutoff allowed.
      Also mention of Ag lost during drilling due to water washing out silver particles. Again, could result in higher Ag production.

      Copper in underlying gravel further west which makes sense as that is directional to Red Hills and Tosca.

      Aurcana has the makings of one heck of a poly-metallic miner. How manly circuits can they put in the plant, lol.

    • Re: Property and mineral ownership:

      <<<The Shafter-Presidio Silver Mine is on private land in the State of Texas. Silver Standard controls 3,500 acres of private land on and around the mine sites (Figure 4-2). Silver Standard also controls, via a lease option taken out in April 1998 by the previous owner RGMC, a contiguous 16,000-acre tract of private ranch land (single owner), which includes the Red Hills copper-molybdenum deposit and several miles of land on-trend between Shafter and Red Hills. This lease option includes the right to purchase significant portions of the tract.
      RGMC has previously purchased all the “major” outstanding royalties on metal production from the Shafter silver deposit. Only the royalty on the very narrow state lease remains and it contains only a minor amount of ore. When RGMC purchased the Shafter property, a 6.25 percent Net Smelter
      Return Royalty was payable to Cyprus Amax out of future mining revenues. RGMC purchased this
      royalty from Cyrus Amax for $50,000 cash and a $475,000 note. The note was reassigned to Silver
      Assets in exchange for Rio Grande stock.>>>

      I assume that when RGMC bought back the from SSRI they received the lease option to that significant tract that includes Red Hills. Ping-pong.

      The Tosca press release mentions a renegotiated deal with vendors:

      I wonder if those vendors include RGMC/Aurcana?

    • Rholls,

      Regarding the open pit at Mina:

      <<<At the Presidio Mine, the massive limestone at the top of the Permian age Cibolo formation is the most favorable to replacement by solutions, and in the vicinity of the mine is known as the Mina Grande Formation. The erosional surface of the Mina Grande Formation developed karst-topography features providing large open areas that served as a series of channel ways for the mineralizing solutions. Where the conditions were favorable, the deposition of silver and base metal mineralization occurred. The Mina Grande limestone, the product of Permian reef formation, has over two miles of strike length of mineralization zones.
      The Permian Mina Grande Formation is unconformably overlain by the Cretaceous-age Presidio Formation and the Shafter limestone unit. Fissures and faults are present in all areas of the mine workings, and a large fault that passes through the Mina Grande Mine area interrupts the continuity of the mineralized zones, and possibly served as a conduit for mineralizing solutions. Figure 7-1 is an East-West schematic cross-section through the Presidio mine-Shafter deposit.>>>

      This would explain the mineralization at the pit and the viability of same. Limestone easily permeable with numerous faults and fissures acting as conduits. Two miles of strike length. I am guessing the Mina fault allowed mineralization upwards closer to surface.

      This would seem to explain Megaw's excitement expressed with the Motley Fool author while driving around looking for the "source". (Peter, feel the source, be the source). Megaw literally wrote the book on this type of carbonate deposit (“carbonate-hosted deposits” because of their irregular but sharp contact with their enclosing carbonate host rocks.) (Megaw, Ruiz, and Titley, 1988).

      No wonder. If he could find the "shoot" it could be a very rich area. Lucrative for Aurcana and a fine feather in his cap.

      Which leads me to another thought regarding Lenic and Aurcana. I need to mull it over first.


    • The Shafter deposit justified the building of the new mill with rich ore.
      The old Presideo mine is being drilled to locate rich new ore deposits not previousely identified as evidenced by the latest drill results.
      The new open pit activity supplies low cost ore and traces of gold. Like La Negra we are probably going see a lot of none compliant ore used. Thats great because it is increasing mine life. It is nice that Aurcana can source ore from multiple locations.
      The old descriptions of the presideo mine and variouse other area mines mention lead and zinc as well as silver and traces of gold. As time goes by and Aurcana adds new circuits to the mill we will see more gold and base metal by products increasing revenues.

    • great digging guys - many thanks.

    • Rholl,

      I talked with Gary Lindsey in IR today. Found some interesting info.

      Evidently the silver they are pulling out of the pit, not the dump, is now averaging 36 oz. Repeat 36. They have been quite surprised by this turn of events. They are still averaging 11% gold per bar. Friday was the 5th pour.

      Per your post relating to Tosca:

      <<<"plus a “potential open-pit resource” of about 3 million ounces of silver averaging about 6oz Ag/ton (Rio Grande Mining Co., 1998a).">>>

      Mr. Lindsey said they now expect to have several years of mining material from the pit not included in the Shafter study.

      His direct number is 720-273-6224 fi you have any questions or wish to verify.

    • You have really found a great deal of good information for us small investors to use to make investing decisions.
      No wonder volume spicked after the weekend tour.
      I would guess that before long we will hear that they are going to speed up the through put capacity...maybe directly up to the 2,500 level.
      I love noncompliant ore. If that prior reference to 3 million ozs of silver in an open pit operation is near accurate the company will be able to concentrate on mine optimization and exploration not just mine production milestones.

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