SERPENTINE, a mineral composed of silica and magnesia in almost eqUal pro portions, with about 13 to 15 per cent of water, and a little protoxide of iron. Serpentine is generally massive; very rarely crystallized in rectangular prisms. COMMON SERPEN TINE sometimes occurs as a rock. It is unctuous to the touch, and soft enough to be scratched by calcareous spar. It is not easily broken, but can be cut without much difficulty. 'It is generally green, black, or red; sometimes uniform, sometimes spotted, clouded, or veined. It receives its name from the serpent-like form which the veins often assume. It is cut and turned into ornaments of various kinds. PRECIOUS SERPI:NTT:cr. or NOBLE is of.a rich dark-green color, hard enough to receive a good polish, translucent; and sometimes contains imbedded garnets, which form red spots, and much add to its beauty. It is a rare mineral. It occurs at Baireuth in•Ger many. in Corsica, at Portsoy in Banffshire, in the Shetland islands, etc. It is generally
found along with foliated limestone, in beds under gneiss, mica-slate, etc., or in com mon serpentine. The ancient Romans used it for pillars and for many ornamental pur poses; and vases, boxes, etc., are still made of it, and much prized. The ancients ascribed to it imaginary medicinal virtues.
Serpentine belongs to the metamorphic rocks. It occurs as an irregularly overlying mass iu the Lizard district of Cornwall, as a dike at Portsoy, and as nodular aggruga dons in the granite of Aberdeenshire. It is generally associated with the gramtoid, igneous, or metamorphic rocks, though it is occasionally found as a member of the trappean series. Trap dikes, in passing through or coming into contact with lime stone, not unfrequently convert it into serpentine, or fill it with lines or masses of ser pentine.