If they are going to produce a concentrate, then it will be taken elsewhere for gold extraction. That is exactly what Si Hughes and I did at Calliachar Burn in 1990. We sunk an opencut on one of the veins, only six inches to a foot in width but a solid rib of pyrite and galena grading very well. We would take out the vein in the sole of this little stope a foot or two at a time, jack-hammer out some footwall for access then repeat. It was developed to some 5.5 metres below rockhead before the winter rains/snows got the better of us. We'd already looked at polished sections of the ore, so were aware of the gold grainsize - mostly microscopic. It all got trucked down to South Crofty for cyanidation there. 6.5 tonnes with an average grade of 158 g/t Au. The Calliachar veins are much narrower than the lodes at Tyndrum, but there are some excellent grades to be found in certain intersections. The primary sulphides ran around 75g/t but there were gossans on top of them that could be dug with a trowel, with channel-samples grading up to 400 g/t over 0.3m. All in all, that was an interesting experience! So far as I'm aware, it was also the first hard-rock gold producer in Scotland, but I may of course be wrong!