Garnet-bearing Sands of the Northumberland Coast

Extract

It has long been known that garnet and other heavy minerals occur in many of the sedimentary beds of the North of England. Among such, where visual proof is easy, are the Inghoe Grits, particularly at Shaftoe, and the Dunstanburgh sandstone at Cullernose Point. Hutchings examined washings of the shales at Seaton Sluice and found zircons in large numbers, along with angular colourless garnet, rutile, anatase, tourmaline, sphene and barytes. In a later study by the same author of the sedimentary beds metamorphosed by the Whin Sill, it was shown that small garnets are very plentiful, especially in the calcareous shales, and are accompanied by augite, hornblende, epidote, sphene, idocrase, wollastonite and other minerals. Kellett made an extended investigation of the heavy minerals in the Coal Measures of County Durham and found 0·4 per cent of these in the sandstone under the Hutton seam (this is the only datum of Kellett's strictly comparable with our results). Zircon proved to be the commonest mineral in these beds; next in order came rutile and tourmaline, while garnet was quite subsidiary.