Fibrolite

The Count de Bournon was the first person to describe this mineral, which he discovered among the substances that compose the matrix of Corundum, whether from the Carnatic or China. From the Count’s description it appears, that it is rather harder than Quartz, of a fibrous structure, of a white or dirty grey colour, and when crystallized forms a rhomboidal prism of about 80° and 100°, but this form he has only met with once. It is infusible; the spec. grav. is 3214; upon collision it emits a deep reddish light. Bournon states, that it cannot by friction be made to give signs of electricity; but Haüy observes, that when insulated it acquires by friction a very remarkable degree of resinous or negative electricity.

Chenevix has given two analyses; one of Fibrolite, from the Carnatic, the other of that from China; the proportion of iron in the latter is the cause of its having a reddish tinge.

The figures of the larger fragments are from those in the British Museum; the smaller figure is from a specimen in a matrix of reddish granite from China: for this I am indebted to the kindness of Sir Joseph Banks, bart.