Green Slate and Shales - PBk19
A range of black mudstones and shales are found across the high fells of the North Pennines, surrounding Alston and beyond.
You notice how quickly your fingers change colour as you pick them up. Because the layers haven’t been compressed and heated, they break easily on the horizontal plain revealing layers of small natural flakes of sparkling Mica.
Surprisingly, when the stone is processed, the yield of colour is low and almost transparent until several layers of paint are built up.
Near Keswick, to the south of Derwent Water, is Borrowdale. At the far end of the valley are spoil heaps of waste and ruins of buildings of the former Graphite mines.
One of these buildings was manned by soldiers guarding the mine entrance, as the mineral was precious during Elizabethan times.
Historically known as wad, Graphite has been mined for centuries for marking sheep, greasing cannons, and making pencils. It is a pure carbon that quickly turns into powder, creating a super-fine silver-grey pigment.
On the other side of the same mountain range are the green slate quarries of Honister.
The waste powder created through cutting the slate has been taken, washed, sieved and processed into a fine transparent pigment that is greyish-green. Highly prized by local artists and almost unknown outside the area.
