Bema makes new discovery at Verde gold depostit in Chile

With the recent discovery of a new, higher- grade zone within the Verde deposit, Bema Gold (TSE) is projecting a sizable increase in reserves at its joint venture Refugio gold project in Chile’s Maricunga district. The discovery was made during Bema’s current 160,000-ft. drill program, the second phase of drilling undertaken by the company since it acquired the right to earn a 50% interest in the project from a Chilean partner last fall. The property is accessible by road and has its own water supply.

The new higher-grade zone, discovered in the western portion of the doughnut-shaped Verde deposit, is estimated to be 2,300 ft. long and up to 700 ft. wide. To date, it has been drilled to a depth of 700 ft., and is still open at depth.

The weighted average grade for all drill hole intercepts within the new zone is reported to be 0.04 oz. gold per ton, with the zone estimated to contain “several tens of millions of tons.”

President Clive Johnson said independent reserve grade and tonnage calculations for the Verde deposit will be released in late August or early September of this year. So far the deposit has been defined over about 4,500 ft. in length, up to 2,000 ft. in width, and more than 600 ft. deep.

The new reserve calculation would incorporate results from the second-phase drill program, including current drilling which is testing a possible eastern extension of a high-grade zone outlined at the eastern end of the Verde deposit during the first round of drilling. Results from drilling in this area are expected shortly.

After its first-phase program, completed earlier this year, Bema announced preliminary reserves of 105 million tons at 0.031 oz. gold (including 75 million tons of oxide reserves grading 0.03 oz. gold) for the overall Verde deposit.

“The discovery of the higher- grade zone provides greater flexibility as to how we will approach the project,” said Johnson. “It provides for the possibility of a faster payback period and a bit more comfort in times of low gold prices.”

Some of the better oxide results from the latest drill program in the new zone are: 230 ft. of 0.044 oz. gold, including 118 ft. of 0.058 oz.; 92 ft. of 0.042 oz.; 66 ft. of 0.062 oz.; and 118 ft. of 0.037 oz. The holes also returned intercepts of mixed or sulphide mineralization at depth.

Bema is spending considerable time and effort to confirm the leachability of the oxide reserves at Verde, particularly as some of the new mines in the Maricunga camp are experiencing startup problems relating to metallurgy.

The company said preliminary results from 18 column tests under way on oxide samples from the Verde deposit confirmed the deposit’s amenability to low cost, cyanide heap leach recovery. It was also noted that agglomeration will not be required.

Samples for the columns were collected from shafts sunk at several locations in the deposit to test the various gold mineralization types, including areas where gold mineralization is associated with higher than average copper grades.

“We were very pleased with the results which indicate all oxide mineralization types are amenable to year-round, heap leaching,” said Johnson. “We also found leaching times and reagent (cyanide and lime) use were lower than we thought.”

Bema reported an average gold recovery of 76% for columns under leach for 30 days with minus one- half-inch crushed material. Columns under leach for 18 days were reported to have showed an average of 66% gold recovery so far, “with all columns continuing to leach with additional recoveries.”

Gus Meyer, Bema’s metallurgical consultant, stated that column test results showed copper in the Verde oxide deposit is having little effect on gold leaching and no problems are expected in recovering gold from solutions.

High altitude column tests are being set up on site, although Meyer isn’t expecting the altitude to have a significant impact on gold extraction (as has been encountered at the Choquelimpie mine at a higher altitude in northern Chile).

Column tests on sulphide material are also slated to begin shortly; however, it was noted that previous bottle roll tests indicated this material may be amenable to heap leach recovery.

Although regulations are much less stringent in Chile than in North America, Johnson said Bema would be running a “North American style” operation with respect to environmental issues from exploration through to project development.

Bema also operates the Champagne heap leach mine in Idaho, which is expected to produce about 24,000 gold equivalent oz. this year.