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Location: |
Foss Barite Mine |
Authors: |
Don Cameron, Graham Smith, Tracy Atkinson |
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Location: |
Queens View & Edradour Distillery |
Author: |
Janet Edwards |
Foss Barite Mine - Don & Graham
Graham had arranged a visit to the Barite Mine through Mr John Christie of M-I GB who, together with the Mine Foreman, collected us from the road end. (Except for Bill who had a puncture and missed the trip. However he consoled himself with a quick run up to the summit of Schiehallion instead). The Foss deposit is hosted in the Ben Eagach Schist Formation of the Argyll Group and is situated on the southern limb of an antiform with a superimposed fold, and the orebody dips steeply to the south. It was discovered by BGS under the MRP project, both Graham and I worked on the exploration at this site.
Splitting into a surface and underground party, we changed into wellies and hard hats and lights for the mine trip with John and the foreman, while Graham took the others round the outside. The mine is a drift or adit working and we descended into the hillside, following the orebody from the 665m level to the 630 m stope, but we couldn’t approach the working face as it was too dangerous. The ore was being brought back from the face and loaded by a small mechanical shovel into two ore cars, which compared to the usual Tonka trucks we see in quarries, were quite small. The mine was very noisy as the two cars shuttled up and down to the surface, struggling with the incline and full loads of the heavy barite.
The tunnel is in the orebody and we could see clearly the junction between the barite and the country rock although any barite remaining was stained black from the exhaust of the machinery. Production is about 1000 tonnes of direct shipping grade barite which is taken to Aberdeen or Yarmouth for milling and then to the drilling sites in the North Sea. The mine has produced 1 Million tonnes since 1984, which is c. 20 % of total UK production since 1900.
Two lucky folks got a ride back up in the ore cars as they didn't think they could make the climb (photo: Don Cameron)
The mine is becoming uneconomic and the company would like to develop the orebody at the neighbouring property of Duntanlich, with a reserve of 7.5 million tonnes barite, The mineral is up to 30 m thick and flexuring is the only type of folding present in complete contrast to the complexly folded Foss deposit. As such the Duntanlich orebody is amenable to low-cost underground mining by modern mechanised bulk extraction methods. Although this is a world-class deposit of a largely inert substance with strategic impact, an application for planning consent to extract around 200,000 tonnes per annum was turned down in the early 1990s following a public enquiry. One of the reasons for refusal was the likely adverse visual impact of the mine access road on visitors to Queen’s View. The mine employs 12 workers and they would be unemployed if the extension doesn’t work.
Foss Mine (7km NW of Aberfeldy) - Tracy
At about 11.30pm Monday, over glasses of wine and much laughter, Graham warned us all to be up bright and early for our mine visit. We had to be at the entrance car park before 8.30am - anyone who didn’t make it on time would miss out – we mustn’t keep John (the manager) and his workers waiting. Never mind that convoy malarkey – just don’t be late!
It was a bright, sunny morning and everyone was on the road by 8am. John and Willie met us to take us to the mine situated at 665m up/over the mountain. The Land Rover ride along the couple of miles of access road was interesting. This gravel, pothole-riddled track was very wet, even icy in parts, and sitting side-ways in the back as we bounced and thumped our way up and over the mountain meant the journey was not exactly a comfortable one.
We had divided into two groups; one to go down the mine first, the other to view surface workings to talk about the geology and discuss the mineralisation. The latter being of great scientific and economic importance as the area probably holds the world’s biggest concentration of barium minerals. Barium is a SEDEX (sedimentary exhalative) type mineralisation. Despite its abundance and importance the mine is probably only viable for three more years.
The first group to go down the mine gathered in the office and saw the extremely complex mine cross-sections and maps showing the underground drives and stopes. Hats and lamps were distributed before we were led to the wellie store where, to our amazement, every size was catered for. All suitably hatted, lamped and now wellied and under the supervision of Willie and Neil, we entered the mine. Treading carefully, we trudged our way through the mud and puddles down the 1:6 drive with only our headtorches for illumination. This descent took us through graphitic schist and then into the barite.
The stope (large cavernous area from which barite had been removed) was 30m high. At the 600m level we saw some barite being piled up by a very noisy dumper. At a few locations there was a wet and shiny orange surface to the walls which looked like typical mineral depositions. Being the tactile person that I am, I decided to have a feel – bad idea – it was all soft, squidgy and slimy – yuk!! Quick – puddle needed.
We occasionally had to wait in wider areas to allow the dumper to come past. At some points we were able to see routes to other stopes above or below us.
Left: After You!! (photo: Tracy Atkinson)
After about an hour underground we began our steep walk back to the surface, although Ann Goundry managed to cadge a lift on the dumper truck so re-emerged in some style!
Above ground we learned more about the basic geology of the mine. The barite is a strata-bound deposit, of about 200m depth, which occurs within the graphitic and muscovite schists of the Argyll Group. The upper mineralization horizon is at the Ben Eagach graphitic and Ben Lawers Schist boundary and the lower horizon is within the Ben Eagach Schist formation. The area was affected by two or three generations of folding and some D2 folding was evident – it was reinverted, so the right way up.
Walking up the slope above the mine entrance, we got some splendid views (whilst gritting our teeth against a biting, sub-zero wind) and were able to identify and collect some good examples of the local rocks. We could see Glen Tilt and the Farragon Hills and had a good view of the open pits where contaminated water could settle.
Right:
The settlement pits and Graham in full flow (photo: Tracy Atkinson)
Contamination of the barite is the introduction of anything that reduces its specific gravity, such as quartz because it is light, although pyrite is acceptable as it enhances the specific gravity so is not penalised.
I can’t possibly finish this write-up without mentioning the facilities. I believe the men were directed to a suitable spot behind a shed but the ladies were ‘treated’ to proper loos in a little portakabin. After the key to The Ladies was found we all followed on, quite impressed … that didn’t last too long. Because of the altitude and subsequent subzero temperatures for much of the year, we were told that running water wasn’t available. We were shown a large white bucket and an ice-covered puddle en-route … hmm! The two toilets just had to be seen to be believed – actually it was best not to look! We were all amazed (don’t think that’s quite the right word) by the enormous growths of mould and various fungi … hovering was definitely the technique to be adopted! We then had the task of flushing with the buckets of freezing cold water – I’m not sure that tipping chunks of ice down them helped the situation but we did our best and they looked a little better when we left than they had we’d arrived. Maybe going behind the shed wasn’t a bad option afterall.
Anyway, we all enjoyed the visit and learned a lot – it’s not every day that visitors are allowed down mines, especially while they are actively mining. Thanks to John and his 12-man team.
Queens View & Edradour Distillery - Janet
This was our afternoon off and it gave us a chance to sightsee. The five of us in Tracy’s car drove north from the mine to famous Queen’s View on Loch Tummel. First of all, we sorted out our priorities and visited the café at the Visitor Centre where they serve excellent generous portions of food. It was a lovely day so we could see Schiehallion away down the loch to the west. To the south, across the loch, is Beinn Eagach, the barite mineralisation that we had seen in the morning actually extends about a kilometre to the east of the hill, where Duntanlich was also seen.
We continued our tourist trail by driving round the back roads of Pitlochry to the Edradour Distillery, the smallest in Scotland. Our guide Frank told us about its history, explaining the copper stills are the smallest legal size for a distillery; any smaller would have been considered small enough to be dismantled and hidden from the Excise in the hills. In the Malt Barn, we watched a video and sampled a wee dram, either the single malt or their liqueur. After a tour of the museum, with its display of products and old machinery, we went over to the working distillery to see the actual process of whisky making. To complete our visit, we bought some goodies at the shop. A quick visit to Pitlochry and its shops rounded off our afternoon out.