Theresa bulk sampling by Duration, Locator

A bulk sampling program is scheduled to begin this month on the Theresa mine property, Duration Mines says. Affiliate company Locator Explorations is an equal partner in the property. Located south of Longlac, Ont., the Theresa was a former gold producer which yielded 4,785 oz from 1945- 1953.

Part of a $3.25-million underground exploration program, the bulk sampling will be carried out during raising between levels, William Hill, a mining engineer and director of Duration explained to The Northern Miner.

Surface facilities have been installed and a hoist is operational. An ore pass is also being driven between the 6th level and 4th level. Gold, which is found in quartz pods and lenses within a series of quartz vein zones, is coarse and free milling, Hill says. Tests completed on core samples show that 75% of the gold is recovered in a gravity jig circuit.

An evaluation completed by Hill of 55 drill intersections through the zones revealed that a majority of the holes failed to yield any assays of value. “These holes went through stopes before being mined and graded 0.05 oz gold per ton. But mined grades averaged 0.19 oz,” Hill explained. Such a discrepency between drill grades and mined grades is not uncommon in free milling quartz stringer-type deposits in the Canadian Shield.

Although the project has no official proven ore reserves, Hill is expecting to have a minimum of 300,000 tons of mine grade outlined by the summer. “I feel that 300,000 tons of ore grade by August is a good target.” An initial study of mine data suggests the property has mineable reserves of 540,000 tons grading 0.2 oz (N.M., Nov 16/87). Potential to add to the mine reserves comes from the newly discovered 3-30 zone which was located after an examination of drill intersections plotted over mine workings. The zone, which is cut by two crosscuts, was sampled on the 3rd level and yielded encouraging results. These included 0.254 oz across 88 ft. Underground drilling has delineated the zone for at least 2,100 ft.

“We have placed no reserve on the zone until we drift and raise on it,” Hill said. He also notes that the 3-30 zone has duplicated what reserves were believed to remain in the main zone.

Pending the successful completion of the current program, Hill feels that by August, the companies will be in the position to make a decision about building a mill. Production is possible by year-end he adds.

As with all gold mining projects where drilling is used to locate and define structures, not grade, the mine “will be a real hands on operation,” Hill adds. Sampling of faces will be performed on three shifts and strict geological control and mapping will be required. “Sampling is a key to this project,” he notes.