ASTERIA.	37
	ASTERIA : the Girasol Sapphire. Pliny thus describes the stone :—" The Asteria, holding the first rank by a natural claim, because it contains a kind of lustre within its substance like the pupil of the eye, and pours it from side to side, when held at an angle, as though it moved about in the inside, presenting itself now from one point, now from another. Also, when held against the sun, it reflects rays of a brilliant white, whence it derives its name (Star-stone). The Indian sort is hard to engrave upon. That found in Carmania is preferred to the others." No description can better suit our Girasol Sapphire, which in its native state is usually somewhat globose, being composed of concentric layers like an onion, to which arrangement its opalescence is due. In this state the light appears as a small orb shifting to and fro within the stone, according as it is turned; but when cut to a plane and polished, this orb becomes a most delicate star of five, or six, silky rays diverging from one centre. This variety is pale and milky: hence the propriety of the term "candicantes," applied by Pliny to its radiance. The character of extreme hardness restricts his description to this kind of Sapphire; for the Adularian Felspar, or Moon-stone (see Solis Gemma), answering to it in some respects, is extremely soft. This latter would indeed seem to be the next stone on his list, the Astrion, also colourless, approaching to Rock-crystal in appearance, pro­duced in India on the coast of Patallene : " within from