On the Occurrence of Vermiculite in England

Abstract

That the discovery of a mineral new to Britain cannot fail to be of interest to geologists, is my apology for bringing the matter before the members of this Society to-day; but my desire is not so much to record the discovery as to obtain the help of those interested in geology in elucidating the geographical distribution of the mineral in question. The district of Furness, in North Lancashire, is rich in glacial debris, and it was during a field-day amongst the Boulder clay, on Walney Island, that the Vermiculite was first found by my friend Mr. C. E. Manby. Walney is a small island separated from Barrow by a narrow channel, fordable in some places at low water, and very probably at one time formed a portion of the mainland. Along the shore, and over the greater portion of the island, there is a mass of glacial debris, in the shape of a heterogeneous assemblage of Granites, Felsites, Quartzites, Slates, &c., &c. Amongst the Granites, the Porphyritic Granite, of Wast-dale, is most common, and when newly dug out of the clay is as fresh, hard, and perfect as if recently detached from the rock; but where exposed to the action of the weather and sea-waves, the boulders are quite soft from decomposition. The Vermiculite is found in both Red and Grey Granite, taking the place of Mica, with Quartz and Felspar; but although I have made very careful examination, I have been unable to trace it in the Shap ...