PROJECTS - Don Sixto (La Cabeza)
Update
As a result of recent political developments in Mendoza Province, Argentina, the further development of the advanced Don Sixto Gold Project has been put on hold. Exeter has filed an action in the Mendoza Supreme Court to have this anti-mining legislation declared unconstitutional and will continue to work with authorities in Mendoza, and with representatives of other mining companies, to effect legislative change.
Project Location
The Don Sixto Property is located in southern Mendoza Province in central western Argentina. The property lies at an altitude of 1200 meters, and the arid character of the area allows good year-round access. The property is close to infrastructure and basic goods and services. The property is controlled through an option agreement between an Argentinean vendor and Cognito Limited ("Cognito"), a 100% Exeter owned subsidiary, whereby Cognito has the right to acquire Don Sixto.
Land Situation
The Company controls 100 square kilometers directly surrounding the Don Sixto Gold Project through Cognito's option, for the acquisition of Don Sixto, with the Argentine vendor. In addition, the Company has options to acquire two additional blocks through Argentine vendors, the first covering 176 square kilometers and the second covering 81.5 hectares which surround the main mineralised zones within the project. The Company has also applied for a cateo covering 100 square kilometers to the immediate south of the Don Sixto deposit.
Early in 2006 Exeter purchased the rights to the surface area of the Don Sixto Gold Project that is presently contemplated for mine development. The acquisition of the "El Pantanito" farm will facilitate the transition of the project from exploration to development, and provides certainty for the landowners most affected by it.
The surface rights cover all of the known gold mineralized zones and the areas considered to be the most prospective for new gold discoveries. In addition, the 8000 hectares include the entire area required for mine infrastructure. The purchase agreement allows the former owners to occupy and manage for stock grazing purposes all lands not required for mining operations. Exeter will build two new houses on the property, located away from any proposed mine development.
Image displaying outline of "El Pantanito" farm
Aerial view of the Don Sixto project area
Geology & Mineralisation
The Don Sixto Prospect lies within a north-westerly trend of steeply dipping and concordant units of rhyolitic (ignimbrites) and sedimentary (volcaniclastics) units belonging to the Permo-Triassic Choiyoi Formation. Gold mineralisation occurs as fine dissemination and blebs in north to north-westerly quartz veins and quartz replacement zones in the ignimbrite and volcaniclastics. The style of mineralisation is essentially a gold-silver, silica-sericite/illite-adularia low sulphidation epithermal system with low pyrite (<2%) and minor clay alteration.
This PDF is an English translation of the original paper:
Delendatti, G.L., 2005: La Cabeza: Un Depósito Epitermal Aurífero de Baja Sulfuración en el Bloque de San Rafael, Mendoza, Argentina. VIII Congreso Argentino de Geología Económica, 15, 16 y 17 de Noviembre de 2005, pp. 199 - 206., Ciudad de Buenos Aires.
Don Sixto Project, Central Vein Zone - Labio vein
Exploration Program by Exeter
Exploration and development programs at Don Sixto Project have been put on hold following the Mendoza Government's decision in mid 2007 to block any potential commercial mine development within the province.
Prior Exploration
Upon acquiring its rights to an interest in the property, the Company commissioned an independent review of all previous exploration results on the property. The review, performed by independent geologist, Ruben Verzosa, confirmed AMD's methodology and resource estimate. The review was used to prepare a drill program and surface channel sampling program to test several zones of near surface gold mineralization that could potentially increase the gold resource. In July 2003, the Company began a field program on the property, including metallurgical testing of available AMD remnant Don Sixto drill samples.
In relation to development studies, the Company's strategy carried out progressive environmental and engineering studies concurrently with exploration. As confidence increases in the economic viability of Don Sixto and provided the Mendoza Government revises its stance on mining in the province, the investigations and studies will ultimately be carried out in sufficient detail to support a definitive feasibility study.
In November 2003, Sandercock and Associates Pty. Ltd. ("Sandercock") of Australia updated the AMD conceptual studies on Don Sixto. This review considered a combination of open pit and underground mining in light of 2003 capital and operating costs. With the positive results of this internal study, in January 2004 the Company planned its first preliminary engineering and environmental work program. The study was designed by Sandercock to work with the results of a detailed drilling program and included metallurgical testing of fresh drill core, geotechnical and hydrological investigations, baseline environmental studies as well as community, infrastructure and transport reviews. Resources were calculated in mid 2005 by independent consultants, Hellman & Schofield. Sandercock completed a preliminary report in late 2005 that provided the basic development concepts for the project and the first factored estimates of capital and operating costs. A financial model was also prepared to provide management guidance and assistance for the next stages of project planning.
2005-2006 Program
Exeter commenced a three rig drilling program in 2005 to expand resources at Don Sixto. Due to the success of the 2005 drilling in identifying extensions of the previously defined gold zones, an expanded program was developed for 2006 exploration at Don Sixto. A total of approximately 40,000 meters of drilling was completed by late 2006 using up to five drilling rigs. Concurrently long lead environmental, social, hydrological and metallurgical studies were conducted to facilitate fast track detailed feasibility studies and, given positive results, development of the project.
Diamond drilling at the Mandibula Zone, Don Sixto
2007 Program
Drilling was suspended at year end 2006, so that the back-log of drill core could be logged, sampled and assayed. This was followed by development of 3D models for each of the zones. Hellman and Schoffield was contracted to provide an independent resource estimate was announced in August, 2007. This will be followed by essentially internal studies to examine resource viability, whilst the Mendoza Government retains its legislation which provides a block on future project viability.
Resources
Results of the new resource estimates at a 0.5 gram/tonne (“g/t”) and a 1.0g/t cut-off are tabulated below:
Table 1: Don Sixto Gold Resource Estimates at a 0.5 g/t gold cut-off
| MEASURED | INDICATED | MEASURED & INDICATED |
INFERRED | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
Mt
|
g/t
|
koz
Au |
Mt
|
g/t
|
koz
Au |
Mt
|
g/t
|
koz
Au |
Mt
|
g/t
|
koz
Au |
|
| Cuello |
1.49 | 1.83 |
88 |
3.80 |
1.39 | 170 | 5.29 | 1.51 | 258 | 1.85 | 1.20 | 71 |
| Ojo |
1.43 |
1.63 |
75 |
1.49 |
1.25 |
60 |
2.92 |
1.44 |
135 |
0.71 |
1.05 |
24 |
| Luna |
1.71 |
1.58 |
87 |
4.51 |
1.23 |
178 |
6.22 |
1.32 |
265 |
1.79 |
1.07 |
61 |
| Mandibula |
2.77 |
1.00 |
89 |
1.77 |
1.09 | 62 | 4.54 | 1.03 | 151 | 4.24 | 0.93 | 126 |
| CVZ* |
0.75 |
2.51 |
61 |
0.76 |
2.24 |
55 |
1.51 |
2.38 |
116 |
0.35 |
1.52 |
17 |
| Cachete |
-
|
-
|
-
|
-
|
-
|
-
|
-
|
-
|
-
|
0.35 |
3.08 |
35 |
| TOTAL | 8.15 |
1.52 |
400 |
12.33 |
1.32 |
525 |
20.48 |
1.40 |
925 |
9.29 |
1.12 |
334 |
Table 2: Don Sixto Gold Resource Estimates at a 1.0 g/t gold cut-off
| MEASURED | INDICATED | MEASURED & INDICATED |
INFERRED | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
Mt
|
g/t
|
koz
Au |
Mt
|
g/t
|
koz
Au |
Mt
|
g/t
|
koz
Au |
Mt
|
g/t
|
koz
Au |
|
| Cuello |
0.84
|
2.68
|
73
|
1.87
|
2.09
|
125
|
2.71
|
2.27
|
198
|
0.84
|
1.78
|
48
|
| Ojo |
0.79
|
2.37
|
60
|
0.62
|
2.03
|
40
|
1.41
|
2.22
|
101
|
0.20
|
1.95
|
13
|
| Luna |
0.91
|
2.35
|
68
|
1.83
|
2.01
|
118
|
2.73
|
2.12
|
186
|
0.52
|
2.02
|
33
|
| Mandibula |
0.90
|
1.63
|
47
|
0.66
|
1.73
|
37
|
1.56
|
1.67
|
84
|
1.10
|
1.60
|
57
|
| CVZ* |
0.46
|
3.67
|
54
|
0.46
|
3.24
|
48
|
0.92
|
3.45
|
102
|
0.15
|
2.62
|
13
|
| Cachete |
-
|
-
|
-
|
-
|
-
|
-
|
-
|
-
|
-
|
0.33
|
3.39
|
36
|
| TOTAL |
3.90
|
2.41
|
302
|
5.44
|
2.11
|
368
|
9.34
|
2.23
|
670
|
3.14
|
1.98
|
200
|
Notes: (*) CVZ or Central Vein Zone comprises the Labio East, Labio West, Labio South and Mercedes prospects.
“Mt” represents million tonnes, and “koz” represents thousand ounces.
The new resources were estimated for 9 prospects using data from a total of 494 drill holes, totalling 56,821 metres (“m”) of drilling and 4,037 m of sawn channel samples (93 channels on 8 prospects), conducted prior to the end of 2006.
The new mineral resource estimates for the Cuello, Luna, Ojo, Mandibula and the Central Vein Zone prospects were made by Hellman & Schofield (“H&S”), of Sydney, Australia following a three week visit to Mendoza at the end of April 2007. The visit, by two representatives, included a two week site visit and validation of the Exeter database, supporting information, and 3-D geological and structural models.
H&S utilised the Multiple Indicator Kriging (“MIK”) method, which estimates the proportion and grade of mineralization for an assumed selective mining unit (“SMU”) within a larger panel (or “block”) for a range of cut-off grades. The deposit is divided into panels (or “blocks”) and in the case of Don Sixto, a panel size of 5 m wide x 25 m long x 10 m high was deemed suitable for the data spacing. Within these panels, two selective mining unit (“SMU”) sizes were utilised: for vertical to near vertical domains, an SMU of 2.5 m width x 5 m length by 5 m height was used and for flat to shallow dipping domains an SMU of 2.5 m width x 5 m length by 2.5 m height was used. The estimates include the dilution incurred when mining the resources at the assumed SMU. This methodology generally results in a resource estimate of higher tonnes and lower grade than less conservative/more standard resource estimation techniques. However, total ounces estimated utilizing the H&S MIK method generally equate to total ounces estimated using less conservative techniques.
The Cachete prospect resource remains unchanged from the previous resource estimation exercise, which was calculated internally by Exeter (in 2005) utilising a manual polygonal cross sectional method of estimation.
The new resource estimates at Don Sixto will be described in a technical report to be compiled by H&S, who are independent of the Company, under Canadian Securities Administrators National Instrument 43-101 and will be filed with the Canadian regulators.
43-101 Report:
Sep, 2007 (Details 5.9 MB - PDF)
July, 2005 (Details 5.9 MB - PDF)
November, 2004 (Details 3.4 MB - PDF)
October, 2002 (Details 1.2 MB - PDF)
Archived Pages
- Sixto Development
- Sixto Geology
- Sixto Drilling
- Sixto Resources
- Sixto Geophysics
- Sixto Geochemistry
- Sixto Regional