Arthur Holmes — The Granophyres of Gar rock Fell. 403 



Table II. 



IV. AlBITE-GrANOPHYRE AND QuARTZ-PoRPHYRY FROM BRANDY GlLL, 



Caurock Fell. 



By Arthur Holmes, A.R.C.S., D.Sc, F.G.S. 



With an analysis by H. F. Harwood, M.Sc, Ph.D. 



Introduction. 



IN the course of an investigation into British resources of sands 

 and rocks for glass-making and refractory purposes, which is 

 being carried out by my colleague Dr. P. G. H. Boswell, it became 

 desirable to search for an alumina-bearing siliceous rock low in 

 iron-content. Among other rocks considered by Dr. Boswell was 

 the granophyre of Brandy Gill, and a sample, obtained from Mr. "W. 

 Hemingway, was submitted to Dr. H. F. Harwood for analysis. So 

 far as industry is concerned, the analysis indicates that the iron- 

 percentage of the rock is too high for its use in glass manufacture. 

 As such an analysis would be of interest and value to geologists — 

 there being few first-class analyses of Lake District igneous rocks — 

 and as it seemed undesirable that only a bare record should occur in 

 a technological publication, Dr. Boswell handed to me the analysis 

 and a sample of the granophyre, with the suggestion that the rock 

 might be described in the pages of the Geological Magazine. 



I am indebted to Mr. Hemingway for two additional specimens 

 of the rock, which occurs near the head of Brandy Gill, west of 

 Carrock Fell. These specimens, though from practically the same 

 locality as the granophyre, differ from it in having somewhat larger 

 phenocrysts of quartz and albite and a more finely grained ground- 

 mass very nearly free from micrographic texture. They are 



