Girasol

Girasol, a precious stone, exhibiting in strong lights a peculiar and beautiful reflection of bright red or yellow light, which seems to come from the interior of the stone. From this it derives its name (Ital., 'sun-turning'). There are different kinds of girasol, variously referred by mineralogists to quartz and opal, species which, however, are very nearly allied. One kind is also known as Fire Opal, which is found only at Zimapan, in Mexico, and in the Faroe Islands. The Mexican specimens are of a rich topaz yellow colour, and the reflection is very bright. Another kind is the Quartz Resinite of Haüy, so called because of its characteristic resinous fracture. It is found of various colours, sometimes of a fine yellow or emerald green, more generally bluish-white. For a specimen of extraordinary brilliancy, not an inch and a half in diameter, £1000 has been refused. The ancients held this stone in high estimation, and called it Asteria (Gr. aster, 'a star'). They obtained it both from Caramania and from India. The brightest are at present brought from Brazil, but fine specimens are also obtained in Siberia. Imitation girasols are made of glass in which a little oxide of tin is mixed.—The name girasol is sometimes given to a kind of sapphire, also called Asteria sapphire, exhibiting a similar reflection of light, and sometimes to Sunstone, an aventurine felspar. According to Castellani, many minerals can be made to reflect light from the interior in the same way as girasol, when they are carefully cut in a spherical or semi-spherical form. He instances adularia, hydrophane (a variety of opal), milky corundum, some kinds of chalcidony, Brazilian chrysolite, &c.