Phase 1 Exploration Program
Currently Aztec is conducing a CAD$139,000 Phase 1 exploration program of structural and geological mapping, soil and rock sampling, trenching and airborne geophysical surveying on the Tombstone Project in southern Arizona is now underway (map link here).
The focus of this exploration program is to better define the three styles of mineralization known to exist on the properties and to identify top priority targets for drilling. The three types of mineralization at Tombstone are as follows:
- High grade silver-gold-lead (zinc-copper) veins cutting Cretaceous Bisbee Group clastic sediments, which hosted most of the historic mines in the Tombstone district
- Bulk tonnage silver-gold epithermal stock-works also cutting Bisbee Group, on which the Contention open pit, heap leach mine was developed in the 1980’s (map link here)
- Potential high grade, bulk tonnage carbonate replacement deposits (“CRD”), which could lie below the Bisbee Group in the underlying Paleozoic limestones, a geologic setting similar to the Taylor deposit of Arizona Mining, located only 65 kilometers southwest of Tombstone, who recently received a CAD$1.8 billion friendly take-over bid by South 32
Tombstone’s Potential Upside
The district is underlain by the same Paleozoic limestone sequence that hosts the massive Taylor zinc-silver-lead deposit of Arizona Mining Inc. located only 65 kilometers west of Tombstone. Arizona Mining is currently the subject of a friendly $1.8-billion takeover bid by South32.
Aztec is primarily interested in discovering new zones of epithermal and CRD mineralization because they typically form much larger mineralized bodies. However, the small historic high grade silver mines are very useful in showing where mineral-controlling structures are located. The geological, geochemical and geophysical surveys will help map the most prospective portions of those critical structures for drilling. The deepest silver mines in the district found the base of the Bisbee Group in the Tombstone district typically no more than 200 meters below surface.
Positive indications for additional shallow, near surface epithermal mineralization at Tombstone include:
- Extensive gossanous mineralized north-south structures remain in both walls of the Contention north pit and the east wall of the central pit
- A 1993 USMX report states their reverse circulation drilling in the Contention Pit outlined a near surface historic mineral resource of 1.15 million tons of 0.063 opt gold equivalent (1.79 gpt) which would now be considered high grade open pit material *see QP Statement
- Historic sample map of the floor of the south pit shows strong silver-gold mineralization that was never drilled
- Historic geological map shows other prospective NS dikes/faults west of the Contention pit
- Historic geological section shows the Contention fault/dikes down dropped and repeated on the east wall of the north pit, and several times further east under cover
- Significant gossanous soil horizon along the west wall of all three Contention pits, suggesting buried oxide mineralization to the west
Positive indications for deeper, underground CRD mineralization at Tombstone include:
- The Bisbee sediments exhibit widespread fracturing, silica-pyrite-sericite-clay alteration, oxidation and in the limey sediments, incipient hornfels and skarn development
- The Contention open pit mine appears to be hosted in the strongest NS structure which not coincidentally is occupied by felsic and mafic dikes possibly related to a deeper intrusion
- The Contention underground mine was developed to a limited extent below the Bisbee Group chasing mineralization
- Five 3000 ft deep vertical Santa Fe drill holes in the west part of the district each intersected narrow high grade CRD mantos, evidence that the Paleozoic limestones are prospective
- The old Prompter Mine shaft and glory hole along the west side of the district show a strong NW structure with low temperature manganese-quartz-calcite veins
- Several manganese-silver rich mines surround the Property and are indicative of distal mineralization to CRD deposits worldwide
- The old Bunker Hill mine located in Paleozoic limestones south of the Bisbee basin produced more tonnes than the old Contention mine, and was strongly polymetallic, again evidence that the Paleozoic limestones are prospective
In summary, historic silver production in the Tombstone district from 1878 to 1939 was estimated at 32 million ounces from several small vein and manto CRD deposits. Aztec management views the district as highly prospective for the discovery of both epithermal and carbonate replacement orebodies.
QP Statement - Joey Wilkins, B.Sc., P.Geo., is the Qualified Person for Aztec and has reviewed and approved the technical disclosures contained herein. The mineral resource calculated by USMX Inc. in 1993 was done manually and incorporated a 45 degree pit slope and tonnage factor of 13 cubic feet/ton. They used silver to gold ratio of 28:1, $4.39 per ounce silver and $374 per ounce gold to calculate a gold equivalent. The mineral resource is a combination of 3 zones, the Contention, Tranquility, and Silverthread with a minimum strip ratio of 5:1. This is a historic mineral resource and the qualified person for Aztec has not done sufficient work to classify the historic resource as a current mineral resource. As a result the Contention geologic mineral resource referred to is not being treated as a current mineral resource.