255 
Along the shore, and oyer 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 exami- 
nation, I have been unable to trace it in the Shap or Wast- 
dale Granite, boulders of which are so plentifully strewn 
over the Furness district. 
The only notice of this mineral I am acquainted with ap- 
pears in Dana's Mineralogy, page 493, wherein it is men- 
tioned as having been named by Mr. T. H. Webb, in the 
American Journal of Science for 1824, and it is described as 
^' Hexagonal, being optically uniaxial. Occurs in small 
foliated scales, distributed through a steatitic base, and 
hence scaly — massive ; lustre somewhat talc-like ; colour 
greyish, somewhat brownish. When heated, exfoliates pro- 
digiously, the scales opening out into long worm-like 
threads, made up of the separate folia. Exfoliation com- 
mences at 500° to 600"^ F., and takes place with so much 
force as often to break the best tube in which the mineral 
may be confined. Occurs at Millbury, near Worcester, 
Massachusetts. Named by Webb, as he says, from the 
Latin Venniculor, I breed worms." 
An analysis follows this description by a Mr. Crossley — 
^' Silica, 3574 ; Alumina, 16 42; Protoxide of Iron, 10 02; 
Magnesia, 27*44 ; Water, 10-30=:99-92." I am able to give 
very complete analyses — both before and after the appli- 
