Native Boracic Acid
- Syn. Native Concrete Borcic Acid. Tennant in Tr. of G. S. 389.
Some time since, my late friend, Ibbetson Fenton, Esq. procured me a case with various natural substances, belonging to the famous Volcanic formation of the Lipari Islands, among which are the specimens figured, which accord with the same substance as described by Mr. Tennant. Its peculiar shining scaly appearance indicates it in the mass, but viewed laterally, it appears fibrous, its fibres being from half an inch to an inch in length, giving it thickness. Probably it often forms in very broad masses on the lava dispersed over the Islands. It is procured only of a size convenient for specimens, some of which, when sent to England, are six or eight inches or more square, and from half an inch to an inch thick. Sometimes it is nearly white and pure, at others it has a mixture of Sulphur, on which it often rests. The artificial primitive crystal is said to be an irregular octaëdron, but it usually occurs so very fiat, as to appear only a very thin hexaëdral plate. It has a peculiar pearly lustre. It is very soft, and separates most readily on the least touch, adhering to the fingers, giving a sparkling talcosc whiteness; on pressing, it offers something of a snow-like resistance, almost creaking. On heating, it becomes a transparent globule, resembling glass, acquiring considerable hardness.