Amianthus

Amianthus (ἀμίαντος, unstained, i e. by sin; Heb 7:3, "undefiled," and so tropically, Jas 1:27; undecaying, 1Pe 1:4; chaste, Heb 13:4), the 'name of a fibrous mineral substance commonly called asbestos. This extraordinary mineral was well known to the ancients. It occurs in long, parallel, extremely slender and flexible fibres; it is found in all countries more or less abundantly, and exists, forming veins, in serpentine, mica, slate, and primitive limestone rocks, the most delicate variety comes most plentifully from Savoy and Corsica. Its fibrous texture, and the little alteration it undergoes in strong heats, caused it to be used by the Eastern nations as an article for the fabrication of cloth, which, when soiled, was purified by throwing it into the fire, from whence it always came out clear and perfectly white, hence it obtained the name of amianthus, or unsoiled.,

By the Romans this cloth was purchased at an exorbitant price, for the purpose of wrapping up the bodies of the dead, previous to their being laid upon the funeral pile, in order to prevent their ashes from being mingled with those of the wood. — Smith's Dict. of Class. Ant. and Penny Cyclopoedia, s.v. Asbestus.