HYALITE

(Yunanca köken — orijinale bakınız.) A yellow or gray variety of uncJeavable quartz or opal; it is commonly concretionary or chalcedonic, of a vitreous fracture anil lustre. It occurs in trap rocks in grains, filaments, and rhomboidal ma es: it is silica combined with about 6 per cent, of water. H Y' [s. 586]