Eaglecrest to extract bulk samples from San Simon

The presence of free, coarse-grained gold and difficulties related to the estimation of resources and reserves have prompted Eaglecrest Explorations (EEL-V) to extract large bulk samples from the San Simon property in northeastern Bolivia, near the border with Brazil.

Over the next seven months, the company plans to extract up to 90,000 tonnes of material from a 700-metre strike area that hosts a vertically stacked series of six flat-lying vein packages. The area also includes a series of steeply dipping, gold-bearing fracture sets that crosscut the flat-lying vein zones.

Eaglecrest retained Kilborn Engineering Pacific to prepare a preliminary, 3-dimensional model of the area using data and “rough geological interpretations” provided by the company. Kilborn was not asked to audit or validate the data or interpretations.

“The model will help us plan our underground program,” says George Cavey, Eaglecrest’s exploration manager. “The work we’ve done so far shows potential for a large, low-grade open pit or a higher grade vertical system that could be mined from the valley floor.”

Using an assumed specific gravity of 2.6 tonnes per cubic metre, the zones were estimated by Kilborn to contain 27.5 million tonnes of “favourable host rock.” Under current disclosure requirements, this volume cannot be classified as either reserves or resources.

Eaglecrest also notes that the presence of coarse gold has made it difficult to determine the grade of the deposit. “We have extreme nugget effect,” Cavey says. “We get numbers all over the place.”

As a prelude to the underground program, Eaglecrest carried out limited bulk sampling in order to get a better handle on grades. The first 92 tonnes, collected earlier this year, returned an average grade of 1.84 grams gold per tonne.

Gold at San Simon is typically associated with the dominant quartz vein sets that strike northeast and dip moderately to the northwest. The veins are cut by nearly vertical-dipping, gold-bearing fracture sets consisting of iron oxide minerals — chiefly specularite and hematite, which produce a net-like appearance. The gold is found to be free and coarse-grained along this secondary fracture system.

The greatest density of veining is reported to occur in the Paititi pit, excavated by artisinal miners. The Buriti pit, 4 km to the west, hosts similar quartz veining, though over smaller dimensions and with a lower vein density.

Cavey says the style of mineralization is similar to that found in the Dome gold mine in Ontario, and the Bralorne gold deposit in British Columbia.

Gold at San Simon was first discovered by Jesuit missionaries late in the 17th century and has been mined (lode and placer) on a semi-continuous basis since that time.