|Mark Patton panning the Fairbanks Placer deposit|
Alaska doesn’t have many roads – you can’t even get to the capital by road, you have to take a ferry. Of the few the State has, I’ve been on about a third of them as part of a residential road trip with the postgraduate Mining Professional Programme run by Camborne School of Mines (CSM). Eight professionals from different mining related disciplines joined Professor Kip Jeffry and Dylan McFarlane from CSM for a ten day trip visiting mining operations which were accessible from the limited infrastructure.
In the first week we met with groups involved with the promotion of Alaska’s natural resources, a core store housing some USGS core, the Wishbone coal prospect operated by Usibelli Coal, the Pogo underground narrow vein gold mine, the Hilltop Gold Prospect, Fort Knox open pit gold mine and Fairbanks Creek Placer Gold Mine. (A placer deposit is where the gold eroded from a vein has been concentrated by a stream and deposited in the sand and gravel on the stream bed). Not one of the mine operations was on a main road. In fact the road to the Pogo mine was 50 miles long and had been put in by the mine to access the operation from the highway. At least that one was wide enough for more than one vehicle. The Hilltop Gold Prospect could be described as ‘unsuitable’ for the hire cars we took along it. The fact that two of our three hosts for that visit were carrying side arms for bear protection just added to the excitement.
|Underground drill bay, Pogo Mine |
Enough about roads though. We were there to see mines and geology and we got that in spade-fulls (and in some cases, pan-fulls). The coal was shiny and black as you might expect but the most striking aspect of the visit to Wishbone was the litter of shotgun cartridges, .22 shell casings and large hunting rifle cases all over the floor of the locality. A bit unsettling, even for a boy from Belfast.
Pogo mine was the highlight of the trip, with a visit to the mill where the ore is processed in the morning, followed by a trip underground in the afternoon. We saw a face getting prepped for blasting, the underground grizzly, a rig, roof support rods getting put in and heard the paste backfill glugging overhead in its way to backfill a stope. Pretty much the full underground package.
|Fort Knox opencast gold mine|
Fort Knox was vast – a much lower grade, high tonnage gold deposit. Here two methods are used to extract the ore. For the higher grades a carbon and cyanide method called Carbon in Pulp is used. A heap leach, where cyanide is trickled through the crushed rock, is used to extract metal from the low grade ore. Getting to hold the ‘Tour Bar’ of doré gold,which had been smelted and poured at the mine, was cool. Eight kilograms and about £200,000 at the market rate. A thoroughly humourless guide was unmoved by all talk of slipping it into a pocket – probably heard it all before.
|Fairbanks Placer Deposit with historic placer barge |
Though Fort Knox was huge it was not the most alarming in terms of perceived impact on the environment. That honour fell to placer mining. Another ‘off the beaten track’ drive to Fairbanks Placer Mine was 10 or 20 minutes in before we realised that what we were driving over was about 100 years of legacy placer mine spoil heaps. Granted, nature was reclaiming what had been left, but that did little to lessen the impact of what had been left behind by methods used in the early 20th century. The current operation was compact and pretty cool to see and we all had a surprisingly successful go at panning whilst there.
The final mine trip was in the second week to the Usibelli Coal Mine. This is the only coal mine in Alaska which, given the coal reserves the State has, is pretty surprising (until you remember what the weather is like and how little infrastructure there is). Our guide was incredibly enthusiastic about the company and the importance of coal in Alaska. Given that 40% of U.S electricity is generated by burning it, it’s easy to see why someone so ‘on message’ was our host for the day.
|Polychrome Pass, Denali National Park and Preserve |
All in all the trip was fantastic. The mineral potential is huge but the State is hamstrung by its size and the lack of infrastructure, something the local businesses involved with developing the mineral (and other natural resource) potential are acutely aware of. The locals are generally friendly and closer to Canadian than American but they are still American and they are staunchly supportive of the military. Like any isolated community they are a bit cut off from the global picture. It’s a long way to go for a lot of driving but the mountain scenery is fantastic and the vastness is hard to take in. It was totally worth the trip and I’m exceptionally appreciative of the opportunity but it’s not somewhere I’d rush back to.
Mark Patton is the Minerals Geologist for the Geological Survey of Northern Ireland (GSNI).