The San Antonio Gold Project is located on the Baja Peninsula, adjacent to the historic mining town of San Antonio and 40 km southeast from the port city of La Paz. Good gravel roads traverse most of the project area and a high voltage power line crosses through it. The 100% owned project covers 46,328 ha and 14 km (about 9 miles) of favorable geological trend. In the late 1990s Echo Bay Minerals located and partly tested the Colinas gold resource and in 2007-2008 Pediment discovered and defined a significant gold resource at Los Planes.
Regional Structure
The Los Planes and Las Colinas deposits are associated with a well defined shear structure, a probable Mesozoic age thrust fault, dipping about 45 degrees westerly. This structure appears to be regional in extent, continuous for at least 20km to the south, where previous work by Echo Bay outlined the Paradones Amarillo deposit (now owned by Vista Gold) which has Measured and Indicated resources of 55 million tonnes grading 1.1 g/t gold.
The Los Planes and Las Colinas zones are located on the northern end of this trend. The drilling at Los Planes and Las Colinas shows the shear zone to be more than 200 metres thick and it has been traced over 3km strike length through Los Planes and Las Colinas. Surface oxidation of the gold bearing sulphide deposits has progressed to about 100 metres in the Los Planes zone and about 25-30 metres in the Las Colinas zone.
These areas are similar to the gold mines of the Mojave-Sonora Megashear that include the 5 million ounce gold deposits at Mesquite in California and at La Herradura in northwest Sonora.
Deposit Geology
Megashear deposits generally contain gold in sheared and broken "cataclastite" and/or quartz vein stockworks contained within shallowly dipping shear zones and thrust faults, hosted by granitic intrusives. Enhanced grades and thickness occurs at flexures (bends) in the faults and intersections with higher angle structures that likely acted as conduits for hydrothermal fluids that carried the gold. The deposits typically have subtle and restricted alteration envelopes of sericite and clay. Gold is associated with sulphide minerals (pyrite, arsenopyrite) that generally represent a minor portion of a deposit volume. Because of a highly fractured character and oxidation of the sulphide minerals near surface, the deposits tend to "weather down" and be hidden beneath overburden.
Exploration Upside
There has been historic mining from two separate deposit types in the San Antonio region. Vein mining of silver-base metal deposits has taken place along the northeast trending El Triunfo Trend, and more limited lode gold mining along a separate and younger north-south trend south of Los Planes and Las Colinas.
The northerly extensions of these two mineralized trends are projected to intersect in a flat lying, pediment covered area immediately north of Los Planes, which constitutes a prime target for discovery of new deposits. In addition, the historic past producing El Triunfo Trend itself is highly prospective for discovery of additional vein type and/or shear zone hosted gold-silver and base metal mineralization. Results from drilling at Los Planes and Las Colinas also suggest the possibility that these 2 zones may be connected but are offset by late faulting, and separated by a highly prospective Intermediate area.
Preliminary Assessment, August 2010
In August of 2010, Pediment announced the results of a Preliminary Assessment on the San Antonio Gold Project prepared by AMEC E&C Services. Based on the results of the Preliminary Assessment Study, AMEC recommends that the San Antonio Project proceed to more advanced studies (Feasibility Study) because:
- San Antonio demonstrates robust financial returns under a $900/oz gold pricing scenario with a pre tax net present value at 8% (NPV@8%) of $79.0 million, and an internal rate of return (IRR) of 33%. The project would annually produce 82,500 oz Au for 8 years at a cash cost $US 513 oz gold. The Capital costs are estimated at $71 million with sustaining capital LOM of $29 million.
- San Antonio PA assumes an 11,000 t/d mine with a conventional truck and shovel fleet with mineral processing via proven heap leaching technology. Contract mining is assumed @ $1.85 /t with ROM for oxide and tertiary (3 stage) crushing for sulphide ores (total resource is split 47% oxide, 53% sulphide). Assumed recoveries are 75% oxide and 50% sulphide.
- Mineral Resource Estimate totals 35.9 million tonnes grading 1.1 g/t Au (oxide grade 0.90 g/t Au and sulphide grade of 1.30 g/t Au). Mine has a reasonable mine life of nine years including a one year pre-strip period with the potential to increase the mine life via resource addition that are currently underway. Strip ratio 2.6:1 (waste to ore).
Updated NI 43-101 Resource Estimate
In August 2009, the Report was prepared for the Company by Melvin Allen Herdrick, MSc., PGeo., Pediment's Vice-President, Exploration, and G.H. Giroux, MASc., PEng of Giroux Consultants Ltd. in accordance with CIM guidelines and NI 43-101 requirements to summarise and confirm previously released results. These include the updated independent resource estimates for the Los Planes, Las Colinas and Intermediate zones completed by G. Giroux.
The updated resource estimates contained, using a 0.4 g/t gold cut-off grade, a total of 1.54 million gold ounces in the M+I category plus a further 111,000 ounces in the Inferred category. The estimates were categorised by their degree of weathering, as follows:
| Mineralization | Tonnes (MT) |
Au (g/t) |
Million Oz. Au |
|||
M&I |
Inferred |
M&I |
Inferred |
M&I |
Inferred |
|
| Oxide | 7.24 |
0.17 |
0.928 |
0.592 |
0.216 |
0.003 |
| Mixed | 6.61 |
0.19 |
1.066 |
0.588 |
0.227 |
0.004 |
| Sulphide | 33.50 |
5.03 |
1.018 |
0.640 |
1.096 |
0.104 |
| Total | 47.35 |
5.39 |
1.01 |
0.637 |
1.539 |
0.11 |
These estimates were based on 242 holes totalling 42,891 metres and comprising 26,613 gold assays. The calculations used ordinary kriging and blocks were compiled over a range of gold grade cut-offs. The values reported here are based on a 0.4-gram-per-tonne gold cut-off. A total of 6 samples in the Planes Domain were capped at 33.2 g/t gold. Based up results of testing by the Company, conversion from volume used a specific gravity of 2.62 for oxide material and of 2.69 for sulphide material. The Report further documents the methodology in greater detail. These estimates update previous resource estimates provided by DMBW based on 124 drill holes totalling 15,804 m and with 14,609 assays that were released on June 16th, 2008 and which are detailed in an independent technical report filed on SEDAR July 15th, 2008.
Project Update
In June 2010, Pediment has begun its third major exploration program with the objective of identifying and exploring new targets in its extensive mining concession holdings, as well as further studying its existing gold resource zones near Planes and Colinas.
The Los Planes deposit area remains open to the south, and has indications from surface sampling that mineralization may extend for an additional 250 m in this direction. East of the deposit, there are anomalous gold values in surface sampling and drill data, in an area adjacent to "the faulted zone".
The area between Los Planes and Las Colinas, termed the "intermediate zone", requires infill drilling, as the current hole spacing is at about 100 m. Existing drilling has intersected anomalous gold values in this region.
The following map displays the deposit area with drilling underway:
Triunfo Zone
The Triunfo holdings were acquired as a group of concessions, under sealed bid auction in 2008, from the Servicio Geological Mexicano, or "SGM" which held the area as a National Mineral Reserve for over 30 years. This historic silver-gold district includes several past-producing mines following the northeast oriented El Triunfo trend which converges toward the north-south San Antonio gold trend near the Planes/Colinas area.
The higher-grade, Triunfo veins are reported to have been mind at an averaged of 6 g/t gold and 328 g/t silver with associated lead and zinc in oxidized veins with widths from 0.3 to 2.5 metres. These extend from surface to up to a depth of 300 meters depth in workings (CRM Tecnico Analysis, Perez and Bustamante, 2008).
Cañada del Agua
The Cañada del Agua mine zone is located in the Triunfo Este Fracc. I concession covering 1,500 meters on-strike, of the mineralized zone about 3 kilometres south of the San Antonio town site. Echo Bay Exploration cut three trenches and drilled six drill holes at Cañada del Agua in 1995-96 (Echo Bay San Antonio Venture Report, Brown, 1996). The exact position of the drill holes, trenches, and validity of the assays have not been verified for the Company by a QP as required by NI 43-101 standards of reporting. The results are included herein for informational purposes and will be checked in this program. The best historical surface results were reported from trench CATR-3 with 12 m of 5.2g/t gold with an additional 10 meters of 0.8 g/t gold. The best historical drill results obtained were 6 m of 1.8 g/tgold in (RC at 60 degrees) in hole SA-95-23 and 22 m of 2 g/t gold in SA-95-35c (core drill hole at 60 degrees).
Aurora
The Aurora trend is located about 2 kilometres south of Las Colinas gold resource, in the same shear zone. The trend extends from the Aurora Mine, an area of old workings just outside the eastern boundary of the Triunfo Este Fracc 2 concession to a gambusino worked area on the southern concession boundary called La Cruz. This zone has a roughly north-south strike with a westerly dip of about 40 degrees. A historical document concerning the Aurora mine (Avirette, 1910) reports workings of more than 40 metres depth that accessed oxidized mineralization for production. The historical reports describe the Aurora mine with assays of mined material of plus 10 g/t gold and plus 200 g/t silver range but these results have not yet been verified and are presented as anecdotal evidence of nearby mineralization only. The north trending ridge that defines the Aurora trend hosts numerous old workings but no drilling has been performed in the area. Mapping, surface sampling and possibly Induced Polarization geophysical surveys are planned to define potential drill targets.
Please click on the following link to view the location of the various target areas and their relation to each other can be found at: http://www.pedimentgold.com/i/pdf/san/SanAntonio-DistrictSchematic.pdf .