ASBESTOS must be considered, in Mineralogy, rather as a term implying a peculiar than sometimes assumed by several minerals, than as a name denoting a particular species ; it is in fact applied to vatic ties of the Amplubolio Minerals, such as Adinolite, Tremolite, which occur in long capillary crystals, placed side by side in parallel position, and thus giving rise to a fibrous masa As might be expected, the above conditions are fulfilled. in various degrees, and there are' accordingly various kinds of Asbestus. Those varieties, the fibres of which are very delicate and regularly arranged, are called Amianthus, a! Greek term signifying unpolluted, unstained. The individual crystals' are here readily separated from each other, are very flexible and elastic, and have a white or greenish colour with a fine silky lustre. Though a single fibre is readily fused into a white enamel, in mass it is capable of resisting the ordinary flame, so that when woven it pro duces a fire-proof cloth, and hence the name from the Greek iiel3sceros, in the sense of indestructible. The most beadtiful specimens have
been found in the Tarentaise in Savoy ; but Corsica must be consi dered as its principal locality, from its great abundance. It is apse found in Cornwall, at SL Neverne ; likewise in several parts of Scot- I land. It occurs also in the United States of Americas, where it is sometimes used as a wick for an oil-lamp.
Those varieties in which the crystals are coarser, with scarcely any flexibility, are called Common Asbestus. It is generally of a dull green, and sometimes a pearly lustre, and readily fuses before the blow-pipe flame. It occurs more frequently than andanthua, and is usually found in veins traversing serpentine.
There are three other varieties, known by the names of Mountain Feather, Mountain Wood, and Mountain Cork, which differ from the Common Asbestus by the fibres interlacing each other. The two first have received their names from their appearance ; the third from its extreme lightness, and from its swimming in water. They have been found in Scotland.