Winston Gold Mining (CSE: WGC; US-OTC: WGMCF) is confident that the past-producing, steeply dipping fissure quartz-sulphide vein systems on its Winston gold property in Montana can extend to considerable depths.
The property — 30 km southeast of Helena, the state capital — is home to two past-producing veins: Custer and Edna. Mining started at Custer in the late 1800s and continued up to the 1930s, while mining at Edna lasted until the 1950s.
The Custer vein was mined continuously for over 732 metres on five primary levels. But little mining was done below the 122-metre level or at an elevation of 1,274 metres, and management says the vein could extend for another 150 metres below that level.
“Custer was the major producer in the entire area and it’s also a big fault that runs all the way through the district, and some of what we’re looking at is related to that Custer fault,” Ben Porterfield, Winston Gold Mining’s consulting geologist, says in an interview.
The Custer vein dips beneath the Edna vein, which is a nearly flat vein with fairly shallow workings. Previous operators stoped up from the Custer to the Edna workings, Porterfield says.
“We know there are a variety of veins close together within this fault zone,” Porterfield says. “Vertical ones, Custer-style, which dip north, and the nearly flat veins like Edna.
“It’s hard to correlate from one drill hole to the next, which is why I’m anxious to get underground. Once you have 3-D geology it will make much more sense, and we can figure out how many veins there are,” he says.
Six drill holes from the company’s 2014 drill program cut intercepts in veins on the western side of the Edna intrusive and found eight vein targets that have never been mined. The vein trend is 150 metres long and open to the east, west and at depth.
“When we drilled there in 2014 we hit high grade 213 metres west of the Edna mine, so now we’re infilling from the Edna mine west to where those 2014 intercepts were,” Porterfield says. “Right now we know there’s a lot of shallow ore that we can get to fairly quickly, and that’s why we’re focused on that area west of Edna, because we know it wasn’t stoped down deeply.”
The company has also just finished two drill holes from the Custer vein and is drilling a third, and should have the assays from the first two holes back fairly soon. “The Custer vein itself goes underneath the Edna vein, so they’re connected,” Porterfield says. “Custer was [last mined] directly below the Edna mine … we plan to continue drilling underneath the old Custer mine … it’s lower priority, and it will take longer to develop, but we need to get more information to plan longer term.”
There are two diamond drills on the property — one is drilling below the Custer workings, and the other west of the Edna mine. So far the company has drilled 12 holes in its first-phase exploration program (1,463 metres over 15 to 20 holes), and in December released assay results from five holes that were collared on two drill pads 31 metres and 61 metres west of the historic Edna mine. The holes confirmed historic drill results and defined the Edna vein trend system, which wasn’t mined deeply in the past.
Highlights included 44.57 grams gold per tonne over 0.7 metre, 69.87 grams gold over 0.3 metre, 23.93 grams gold over 1.2 metres and 4.52 grams gold over 0.5 metre.
“We’ve hit some stuff we like and will probably extend the drill program,” Murray Nye, the company’s president and CEO, tells The Northern Miner. “From where the old Edna workings are, there is maybe 800 feet of strike that we’d like to define, and we believe there are two or three veins in that zone that we call the Edna trend. We’ve got the drills set up and are drilling where we think they mined the Custer vein, so we will probably continue on there in 2017.”
Nye notes that phase two will involve test mining and bulk sampling. Montana’s small miner’s permit allows the company to access, test and mine the veins quickly, he says, and the company intends to start a bulk sample with test mining at a rate of 150 tonnes per day, and ramp up to 230 tonnes per day if possible.
“Once we get underground we can get a better idea of the orientation of some of these veins,” he says. “We can access the area quickly with a decline or an adit. It’s not like sinking a shaft.
“The small miner’s permit means you can operate underground and allows limited surface disturbance,” he continues. “The permitting is quite reasonable and it gets you underground, and gives you a chance to figure things out.”
The company is also planning an exploration drift to the Edna mine from historic workings at the Old Hyantha lead-silver mine, a few hundred feet south of Edna. The Hyantha adit will be expanded for 122 metres, then continue another 213 metres, Porterfield says.
“Old Hyantha was a lead-silver mine south of Edna at a lower elevation, and they were partway into the mountain towards the direction we’re interested in. We’d have to slash it open bigger for modern mining equipment, but it’s quicker to open up a smaller, older adit than start a new one.”
Porterfield, who spent much of his early career working for larger mining companies like Kennecott Exploration, says working on narrower underground vein systems like Winston “is interesting and a lot of fun.
“We saw this niche in Montana with these high-grade veins,” he says. “No one was even looking at them. This is an opportunity because there are a lot of underground mines and quite a few of them have potential, and no one really knows how to do it, and nobody is interested.
“All of my friends were open-pit geologists and engineers, and there’s no way they could wrap their minds around a narrow, high-grade vein system,” he continues. “The focus and the big money moved to open-pit mining, and that’s what everybody wanted.”
Porterfield adds that Montana’s ban on using cyanide in open-pit mining also discouraged many mining companies from exploring in the state. But he says if ore comes from underground mines it can be custom milled at grandfathered treatment plants, such as the one at Barrick Gold’s (TSX: ABX; NYSE: ABX) Golden Sunlight mine.
Golden Sunlight, 55 km east of Butte, produced 68,000 oz. gold last year.
“People have shied away from Montana, but we actually like working there,” Porterfield says. “It was controversial when that cyanide ban initiative was put in. People hear the word cyanide and they don’t understand that it’s basically a fertilizer … if people could have been educated about cyanide a little more it would never have happened. But that’s why we’re sticking to underground mining projects.”
Porterfield adds that the management team at Winston Gold — which founded RX Exploration and includes Harold (Mike) Gunsinger as operations manager — were involved in restarting the Drumlummon gold-silver mine, 32 km northeast of Helena, Mont., in 2010, and are on good terms with regulators in the state. The group later lost the asset in a proxy fight.
“We got to know the Department of Environment Quality and regulatory people in Montana, and we managed to open up that mine and do it well, and developed a good working relationship with regulators, because we never tried to do any funny business,” Porterfield says. “We have a lot of experience in doing this and know the people involved, and hire the best consultants, so we’re not intimidated at all permitting in Montana.”
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