Rockgate defines large roll-front uranium deposit in Mali (February 04, 2008)

If Rockgate Capital (RGT-V, RCKGF-O) has its way, the West African nation of Mali will one day become as well-known for its uranium deposits as it is for being the home of the legendary city of Timbuktu — a powerful trading hub in the 15th century and an influential centre of Islamic learning.

After 20,000 metres of drilling in western Mali, about 20 km north of the country’s border with Guinea, near the village of Falea, Rockgate believes it has a “large and compelling” uranium exploration project on its hands.

“I’m quite optimistic because of the fifty-five holes we drilled, fifty-two had uranium in them,” says Lorne Warner, Rockgate’s vice-president of exploration. “And the zone itself remains open in almost every direction, we haven’t closed it off.”

Rockgate is exploring for uranium and copper mineralization at the Falea property in partnership with Delta Exploration (DEV-V, DEVDF-O).

Significant uranium and copper values were first discovered at Falea by Cogema in the late 1970s, but the project was not advanced because of low commodity prices. Cogema, now part of French energy giant Areva (ARVCF-O), had mapped and tested the area in an 86-hole program.

Rockgate and Delta are now defining and expanding those initial results. So far, the first phase of 55 diamond-drill holes has revealed uranium mineralization in the central zone with an average thickness of 3.7 metres and an average grade of 0.1% uranium oxide, which remains open in almost every direction.

“(That’s) a very viable grade from which we believe we can build a sizable resource,” says Karl Kottmeier, president of Rockgate, in an interview from his Vancouver office. “We’re still drilling right now and we will be continuing with our drill program and we hope to initiate a resource calculation in early 2008.”

The mineralization appears to be a classic, flat-lying, sandstone rollfront uranium deposit, bounded by mudstones, the company said in a press release. It also has a northwest trend of 1 km in length, with an average width of 250 metres in the core zone. The mineralized zone occurs at an average depth of between 260 and 275 metres.

“Most of our drilling to date has been on one-hundred-metre centres, whereas larger uranium companies do it at fifty or twenty-fivemetre centres,” Warner says. “In terms of first-pass drilling, you’re not usually that aggressive. But we have the confidence in what we are seeing, so we moved out to one-hundred-metre centres almost immediately.”

The 150-sq.-km property is situated on a relatively flat plateau with scattered, low rolling hills and a few shallow rivers. The area is in the Falea-North Guinea-Senegal basin, described as a Neoproterozoic sedimentary basin “marked by significant radiometric anomalies,” the company said in a statement.

“Preliminary reviews of the sandstone porosity in mineralized core, surrounded by mudstones, suggest that in-situ leach recovery is a possibility,” Kottmeier says. “We’re going to do porosity and permeability tests on the core in early 2008.”

Drilling has encountered several mineralized intersections including hole DF-016, which cut 4.9 metres (from 284.9 metres down-hole depth) of 0.12% U₃O₈ along with a higher-grade 0.9-metre interval that ran 0.46% U₃O₈.

Hole DF-036 also hit a 4-metre intersection of 0.18% U₃O₈ (from 264 metres) and hole DF-050, a 5-metre interval that ran 0.17% U₃O₈ (from 290 metres).

Several drill sections returned grades of 0.04-0.1% U₃O₈ over widths of between 2 and 6 metres.

“This is the first zone of several that are known on the property,” Warner adds. “We are now getting even more aggressive and we are moving our diamond drills 1.5 kilometres to the north and I’m drilling at twenty-metre spacings.”