Seen in Glen Lochay, Perthshire - grid ref NN456357 but on a boulder that's presumably been moved a bit by a glacier. Lots of garnets in the glen but not on this boulder.
Geological maps mention 'graphitic schist' hereabouts. Is this graphitic schist? (image below and attached as lochayschist.jpg) It does look a bit like fossil plant remains as seen in Carboniferous rocks, eg Fife coast. But as the rocks in Glen Lochay are Precambrian, plant remains are impossible. So the follow up question: if this is graphitic schist, where does the graphite come from?
The streaky bits have a golden sheen. I also saw this sort of rock, with the streaky bits rather blacker, on Beinn Heasgarnich NN420390 approx (attached photo heasgschist.jpg without centimetre scale).