In Spain, the specular-stone is extracted from shafts sunk in the earth to a very considerable depth; though it is occasionally to be found just beneath the surface, enclosed in the solid rock, and extracted without difficulty, or else cut away from its bed. In most cases, however, it admits of being dug up, being of an isolated nature, and lying in pieces, like rag-stone, but never known as yet to exceed five feet in length. It would appear that this substance is originally a liquid, which, by an animating power in the earth, becomes congealed like crystal; and it is very evident that it is the result of petrifaction, from the fact that, when animals have fallen into the shafts from which it is extracted, the marrow of their bones becomes transformed into stone of a similar nature, by the end of a single winter. In some cases, too, it is found of a black colour: but the white stone has the marvellous property, soft as it is known to be, of resisting the action of the sun and of cold. Nor will it, if it is only protected from accidents, become deteriorated by lapse of time, a thing that is so generally the case with many other kinds of stone that are used for building purposes. The shavings, too, and scales of this stone, have been used of late for another purpose; the Circus Maximus having been strewed with them at the celebration of the games, with the object of producing an agreeable whiteness. CHAP. 46.—PHENGITES. During the reign of Nero, there was a stone found in Cappadocia, as hard as marble, white, and transparent even in those parts where red veins were to be seen upon it; a property which has obtained for it the name of “phengites.”[2771] It was with this stone[2772] that Nero rebuilt the Temple of Fortune, surnamed Seia,[2773] originally consecrated by King Servius, enclosing it within the precincts of his Golden Palace.[2774] Hence it was that, even when the doors were closed, there was light in the interior during the day; not transmitted from without, as would be the case through a medium of specular-stone, but having all the appearance of being enclosed within[2775] the building. In Arabia, too, according to Juba, there is a stone, transparent like glass, which is used for the same purposes as specular-stone. CHAP. 47.—WHETSTONES.