Chrys'olite

Chrys'olite (Gr., 'golden-stone'), a mineral composed of silica, magnesia, and protoxide of iron; of a fine yellowish-green colour, with vitreous lustre; transparent, and having double refraction; in hardness, about equal to quartz; and with conchoidal fracture. It often crystallises in four-sided or six-sided prisms, variously modified. Very fine specimens are brought from Egypt and from some parts of the East, also from Brazil. Chrysolite is used by jewellers as an ornamental stone, but is not highly valued. Olivine, or com- mon chrysolite, is an important rock-forming mineral. It is dark yellowish-green in colour, and occurs generally in somewhat rounded grains or corroded crystals in some igneous rocks, such as the basalts. Occasionally large granular masses, which may have a rectangular outline, are met with in lavas—some of them weighing as much as 30 lb.