The Mojave-Sonora Megashear hosts millions of ounces of gold production, reserves, and resources. The most significant gold mine along this structure is La Herradura. It is the largest producing gold mine in Mexico with resources of more than 8 million ounces, and is located only 50 km from El Antimonio.
The area is experiencing a major exploration boom which started just two years ago because of new discoveries, La Herradura increasing their mined reserves due to their exploration success, and the price increase of gold and silver.
Many of the mines currently in production started with small mining prospects that underwent new geological interpretations or were explored in several stages. The exploitation of antimony and minor gold and silver, along with the 50 veins in the El Alamo Range district, presents a perfect opportunity to explore for a mineable gold deposit at El Antimonio.
The potential at El Antimonio is considered significant in view of several factors:
Urastar Gold Corp. is excited about the potential for this excellent property!
The exploration target is a bulk mineable gold deposit centered on previously mined veins and new areas discovered through recent field work. Six main and ten minor areas with gold values or mining workings have been defined; the focus of those targets is the alteration and stockwork quartz veinlets developed between quart veins.
Urastar has recently completed 10,517m in 49 holes of RC drilling. Thirty-seven of these holes intersected mineralized zones including several wide gold bearing intercepts. Urastar considers these results to be highly significant and indicative of the potential for a bulk tonnage gold deposit. Several high potential targets remain untested as the majority of the project area remains unmapped and sampled.
Urastar CEO, Adrian Robertson, P.Eng., comments:
“These results cap off a very successful phase 1 drill campaign and add to the significance of the property and its high potential for a large, bulk tonnage gold deposit. Planning is underway for an aggressive exploration program at El Antimonio in 2013. The focus of next year’s work will be to expand on the success we had in the border zone and dead man zone and also to drill several high potential targets we weren’t able to test as part of this year’s program.”
It is suggested that there is excellent potential for an open pit gold mine in this area.
Drill cutting samples were submitted to ALS Minerals in Hermosillo for preparation. Sample analysis was done at ALS Minerals in North Vancouver, Canada for gold by the Fire Assay method on 30 gram subsamples with AAS finish. ALS is an independent ISO certified commercial laboratory. Quality control included monitoring results of certified reference standards and submitting duplicates and blank samples with the samples. Intervals are measured down the hole and may not represent true thickness.
Dr. Matt Ball, P.Geo., Is a Qualified Person pursuant to National Instrument 43-101 who has reviewed this technical information.
Several clusters of veins have been previously mined for antimony within an area extending over 6 km x 4 km. In each cluster, one or more veins have been excavated by pits, or stoped along the structure and accessed by shafts or adits.
Historically, there has been production of antimony and gold from placer workings of gravel. The overall amount mined appears to be relatively small (less than 250,000 tons).
Today, prospectors are recovering small amounts of gold nuggets from gravel using metal detectors. The nuggets do not appear to have been transported very far as they are fairly coarse and not rounded or flattened.
In 2009, a total of 42 samples were collected from historic workings and altered outcrops over an area of over 4 km x 2 km. These workings are sited on vein swarms, with each swarm localized within areas approximately 0.5 km square.
Further sampling was done in October of 2010, following acquisition of additional ground.
Several samples from the 2009 campaign returned elevated gold values ranging up to 2.15 g/t Au, with the average of all 42 samples collected being 0.316 g/t Au. Silver results are elevated and range up to 68.5 g/t Ag, and antimony is high (over 10,000 ppm). Elevated values for several other metals were obtained including As, Ba, Mn and locally Pb and Zn.
The results are considered highly significant because most of the samples are of altered and weakly mineralized material that was left behind, so the ore grade material that was mined is not included in the average.
The best sample, in terms of grade x width, is 1.23 g/t Au over 5.2 m, which was a chip sample across a ferruginous siltstone containing 10-20% quartz stringers. This sample demonstrates the presence of open pit ore-grade material in altered sedimentary rocks that were not previously mined.
*The reader is cautioned that these results are preliminary in nature and are not conclusive evidence of the likelihood of the occurrence of an economic mineral deposit.
All samples were analyzed at ALS Chemex in North Vancouver by Fire Assay for gold, and either AA or ICP techniques for silver, base metals, and pathfinder elements. QA/QC procedures included the insertion of blanks and standards in the sample stream at a frequency of 10%.
Location & Geology
The El Antimonio property consists of 12,500 hectares and is located 40 km west of Caborca, Sonora, in the heart of the Mojave-Sonora Megashear.
The host rocks are various sedimentary rocks including Permo-Triassic limestone, Jurassic arenite, and Cretaceous arenite, all intruded by upper Cretaceous-lower Tertiary diorite, and Tertiary rhyolite and rhyodacite.
Highly ferruginous argillaceous sedimentary units, that host low-grade gold, are present.
The mineralization is low sulphidation Sb, Ag, Au veins; mesothermal style with a late-stage epitheral overprint. Quartz veins, vein breccia, quartz veinlets, and silicification associated with faults and shear zones cut sedimentary rocks including siltstone, greywacke, and local limestone.
The vein quartz is of two types:
The two types occur together in fault zones that are associated with purple hematitic altered wall rocks. The hematite iron oxide is a supergene weathering product of original sulphides presumed to be pyrite. Sulphide mineralization is rare within the vein quartz, and consists of patches and small seams of black-grey fine-grained sulphide.
Alteration is generally widespread and consists of argillization with limonite and/or hematitic iron oxide staining that extends a few hundred meters around the mined fault/vein structures. The altered zones commonly contain quartz stringers (10% quartz). There are large areas of alteration and some quartz veins that have never been pitted or mined.
All of the historical workings are located on discontinuous quartz veins and quartz stringer zones associated with faults. Several orientations of vein/fault structures are developed. The deposit is characterized by large areas of altered rocks containing intense fracture networks and crackle breccias, with hematite and/or limonite coatings on fractures.
In a signed Letter of Intent, Urastar can earn a 100% interest in the El Antimonio project by making the following option payments over a 5 year period:
Payment schedule in USD:
$10,000.00 on signing
$40,000.00 on approval of TSX Venture Exchange
$50,000.00 on 1 year anniversary
$25,000 at drill mobilization
$75,000.00 on 2 year anniversary
$150,000.00 on 3 year anniversary
$200,000.00 on 4 year anniversary
$1,450,000.00 on 5 year anniversary
In addition, the owners will retain a 3% net smelter return (“NSR”) royalty on the Property, subject to the right of Urastar to purchase each 1% of the NSR (namely a 1% NSR) for $1,000,000.00, for five (5) years after signing. The Letter of Intent is subject to TSX Venture Exchange approval.