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Lindero is a porphyry gold deposit located 250 kilometres west of the city of Salta, northwestern Argentina and 12 kilometres southeast of the Company's Rio Grande property. Access is by all-weather road from the City of Salta or Chile.
Lindero is 100% owned by the Company. Mineralization on the property was initially discovered by the Company's exploration team in September 1999.
In 2002, Rio Tinto Mining and Exploration Limited ("Rio Tinto") conducted two diamond drill programs comprising 3,278 metres in ten holes at Lindero. Upon examination of the exploration results, Rio Tinto undertook a reverse economic study entailing further metallurgical testing, three-dimensional modeling and a logistical review of the Lindero deposit. Upon completion of the Reverse Economic Study when gold was valued at less than US$270/ounce, Rio Tinto determined that Lindero was unlikely to meet its size threshold and returned the property to Mansfield in March 2003.
In September 2003, the Company announced the results of an independent resource estimate on the Lindero deposit. The estimate was audited by Roscoe Postle Associates Inc. ("RPA"), an international company of consulting mining and geological engineers, and was based upon drilling, assay data, and block models generated by Rio Tinto.
In RPA's opinion, a preliminary cut-off grade for a deposit of this type, located in a remote region of Argentina and mined via open pit, would be 0.6 grams/tonne gold. After application of this cut-off grade to the Rio Tinto block model, the Inferred Mineral Resource estimate is as summarized below.
RPA RESOURCE ESTIMATE
0.6 gram/tonne Gold Cut-Off, All Inferred |
| Zone |
Tonnes |
Gold (g/t) |
Ounces Gold |
| MVZ |
20,604,000 |
1.15 |
758,500 |
| PVZ |
4,126,000 |
1.23 |
163,200 |
| Di P2 |
5,223,000 |
0.68 |
114,200 |
| Total |
29,953,000 |
1.08 |
1,035,900 |
The above zones occupy an area 600 metres long by 200 metres wide along the southeast flank of a prominent hill.
The Company has received the results of metallurgical testwork completed by Kappes, Cassiday and Associates under the supervision of Thomas L. Nimsic of American Au-Ag Associates. The results of the bottle roll and column metallurgical testing show that:
- Lindero mineralization is amenable to extraction of gold using cyanide;
- In the tests, approximately 70% of the gold was recovered in 100 days. With long term leaching in the field recoveries should be expected to be somewhat more than the tests as the columns were still recovering slowly at 101 days;
- NaCN consumption will be approximately 0.6 kg/tonne;
- Caustic lime consumption will be in the range of 1.25 kg/tonne; and
- The optimal crush size range is between 12.5mm (½") and 19mm (¾").
Gold mineralization at Lindero is hosted in the Lindero porphyry. Potential ore grade gold mineralization in the main zone is principally hosted in an intense magnetite and quartz-magnetite stockwork. Strong mineralization correlates with strong potassic alteration. To date, work at Lindero has included geologic mapping, soil geochem, trenching and 115 holes of diamond drilling.
The following tables are a synopsis of trench and drill results of both the Phase I and II programs.
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