Etruscan works gold targets surrounding Koma Bangou

With the uranium boom long past, the impoverished West African nation of Niger is pinning its hopes on gold. Canada’s Etruscan Enterprises (VSE), in turn, is turning to Niger for its future.

When The Northern Miner visited the property, activity was abounding, most notably in the form of reverse-circulation (RC), auger and diamond drilling. And still more drills were reported to be on their way, as were more geologists, bringing the personnel total close to 200 and the number of drills to six.

Etruscan’s 170-sq.-km Koma Bangou property, in southwestern Niger just east of the Burkina Faso border, is the most advanced gold property in the country. It lies within the Tera-Gassa greenstone belt, one of the lower Proterozoic-age, volcano-sedimentary districts in the West African craton.

Gold was discovered at Koma Bangou in 1985 by a shepherd. Within a few weeks, more than 20,000 orpailleurs (artisanal miners) were on site, digging pits wherever quartz veins were exposed. By 1987, the Nigerien government had sent orpailleurs packing and dispatched a crew from ONAREM, the state-owned exploration company, to Koma Bangou. Over the next few years, ONAREM explored the property, mostly in the area of the orpailleur diggings.

Etruscan was granted permission to explore the property in 1994 and, in January 1995, signed a mining convention with the Nigerien government for the right to mine Koma Bangou. Etruscan strayed farther from the orpailleur pits than ONAREM, and early in 1995 the strategy paid off, with the discovery of V1 South — a low-grade, bulk-tonnage gold deposit within the property’s Central zone.

The area known as V1 South hosts what Etruscan believes is a geological resource minable by open pit. It is estimated to contain at least 9 million tonnes (down to a vertical depth of 90 metres), with a grade of between 1 and 1.5 grams gold per tonne.

The intense heat of the Nigerien climate has rendered near-surface geology a challenge, but most of the disseminated gold appears to be hosted by an intrusive, felsic porphyry and, in places, the adjacent sediments.

“We don’t yet know why [gold] is going into the sediments in certain areas,” said project manager Donald Burton. The better grades have been found near the contact between the porphyry and the sediments, where fracturing aided the movement of gold-bearing fluids, and Burton has decided to increase the spacing of the latest diamond drill holes on the Central zone to 100 from 50 metres, “because we want to look at as much of the contact as we can quickly with core.”

Grade, however, will not be as important as size if the similarity (away from the contact) between the porphyry and the sediments extends to gold mineralization.

“When you look at the contact between the porphyry and the sediments, they have the same characteristics — silicification, ultimately manifested as white quartz veins on the contact. Plus, there is the same sulphide assemblage in the sediments as in the porphyry.”

Throughout the property, drillers must penetrate 80 metres of sand and laterite before fresh rock is encountered, making reverse-circulation and auger drilling important exploration tools. ONAREM’s data have been based primarily on 11,000 metres of RC drilling. Etruscan has since added 20,000 metres to that amount, plus 6,000 metres of auger drilling and 3,500 metres of diamond drilling.

Using the auger drill, Burton explained, “we drill through the laterite, through the mottled zone (generally about 4 metres of transitional material), and then, once we get a metre that’s clean, we take the next metre as our sample.

By spacing the holes 100 metres apart, Etruscan is covering 500 square metres a day, which is necessary for a property as large as Koma Bangou.

Burton explained: “What we try to do is delineate the mineralized zone with auger drilling, bring in the RC drill to drill down to 120 metres to establish the continuity of the mineralized zone, and then bring in the core drill behind it.

“Each hole we drill, we’re learning something new. We’ve only had core to look at over the past month or two, and despite all the work we did with the RC chips, it was really hard to get geological information before the core drilling.”

In recent weeks, core drilling has revealed that the disseminated gold found in laterite is also present in the underlying fresh bedrock. One hole intersected 1.45 grams gold between 98 and 169 metres below surface.

At Koma Bangou, Etruscan is also conducting exploration on geochemical anomalies that had been defined by “termite mound sampling.” (Termites burrow to bedrock in search of the water table and bring material back up with them.) Analysis of mounds in the vicinity of V1 South indicates that the zone could extend for another 1,000 metres along strike.

Etruscan has also begun drilling the Grande zone, an area of coincidental ground magnetic and (termite-mound-based) geochemical anomalies, where grab samples averaged more than 7 grams gold.

Elsewhere on the vast property, Etruscan has noted discrete, high-grade gold mineralization in quartz veins, mostly where orpailleurs had left off mining. The wall rock at these locations did not run, however, so the company considers these areas to be no more than small sources of high-grade ore with which to sweeten its millfeed.

Etruscan recently began working on a promising quartz-tourmaline structure, which runs for more than 16 km on the property, and another 34 km south of Koma Bangou. Its width at Koma Bangou ranges from 4 metres in the north to 20 metres in the south, and visible gold has been found at several locations along the structure.

Burton said the quartz-tourmaline system appears to be similar to that found at the Loulo gold deposit in Mali, Niger’s neighbor to the northwest. Loulo, which is defined down to 150 metres, grades between 4 and 4.5 grams gold per tonne.

“We’ve got all the right ingredients there to find that type of deposit,” he said.

Etruscan has been using both bottle roll leaching and bulk leaching by means of cement mixers at its laboratory in the Nigerien capital, Niamey, to determine rough grades and recoveries. Using the cement mixers, a 20-kg sample can been processed in 12 hours.

Unfortunately, samples sent to an African laboratory for fire assay have become backlogged, making it necessary for Etruscan to begin sending samples to Chemlab in Vancouver, B.C., and another lab in Denver, Colo. Results are expected shortly.

For its laboratory work, Etruscan has made use of the Technical University of Halifax. “We tell them what problems we’re having and what we want to do, and they tell us what scale to go to and what reagents to use,” Burton said. “They work with it there, they come up with the right recipes, and then tell us so that we can apply it here.”

All of this lab and field work at Koma Bangou is costing Etruscan $600,000 per month. But with more than $2 million in its treasury dedicated to Koma Bangou and with increasing support from Echo Bay Mines (TSE), Secretary-Treasurer Angus MacIsaac is not concerned.

Echo Bay first took an interest in Koma Bangou in March, when it acquired an option to earn a 44% interest in the project. It also accumulated, through several block purchases of common shares, a 27% interest in Etruscan itself.

Should Koma Bangou proceed to production, the ownership would be divided as follows: Echo Bay (the operator), 44%; Etruscan, 23%; ONAREM, 23%; and the state of Niger, 10%.

Once possible, probable and proven reserve totals are supported by a feasibility study (expected by September 1996), Echo Bay will pay Etruscan US$20 per oz. for the first 1 million oz. gold and US$25 for each additional ounce.

“It was a good deal for us, a better one for Echo Bay,” said MacIsaac. And while MacIsaac regards the auger and reverse-circulation drills as “just exploration tools,” he expects the tonnage of the gold resource at Koma Bangou to rise dramatically once all four diamond drills are turning on the property in the next few weeks.

With the ongoing exploration of areas far removed from the Central z
one, MacIsaac figures the resource total could jump to 20 million tonnes. “It really is going to mushroom.”