Serpentine
Collier's New Encyclopedia (1921)
an abundant mineral occurring in one or other of its numerous varieties in all parts of the world. Crystallization, probably orthorhombic, but when found in distinct crystals always pseudo-morphous. Occurs usually massive, but sometimes fibrous, foliated, fine granular to cryptocrystalline. Color shows many shades of green, yellow; streak, white, shining ; translucent to opaque; fe feel, greasy; fracture, either conchoidal or splintery. Composition: Silica, 44.14; magnesia, 42.97; water, 12.89= 100, corresponding with the usually-accepted formula, 2MgOSiO2+MgO, In petrology, a rock, consisting essentially of a hydrated silicate of magnesia, resulting from the alteration of magnesian rocks, of all geological ages, especially those of olivine . It contains also some protoxide of iron, and other impuricolor, which is often of a dull green, but ties which cause a great variation in is also marbled and mottled with red and purple. It takes a high polish, and is turned into ornamental articles . The accessory minerals are numerous, the most frequent being pyrope, bronzite, magnetite, and chromite. In geology, serpenrock, originally a trap or dolerite with tine is considered an altered intrusive olivine. town, 57 miles by rail S. of Moscow, on SERPUKOFF , an ancient Russian the Nara, 3 miles from its confluence with and was before the World War, a place the Oka. It contains a cathedral ( 1380), of considerable commercial and industrial tons, woolens, leather, paper, furniture, importance, manufacturing chiefly cotand earthenware. Pop. about 31,000. It was formerly a fortress protecting Moscow on the S. in tufts attached to the head and anterior Annelida, whose organs of respiration are
What Has Changed in the Last Century
Collier's in 1921 called serpentine an altered intrusive rock, originally a trap or dolerite with olivine, and gave it a single formula. Since then it has been resolved into a group of sheet silicates, chiefly lizardite, antigorite and chrysotile, and the rock serpentinite is understood as hydrated mantle peridotite, much of it emplaced on land as ophiolite slices or forming at mid-ocean ridges and subduction zones, ideas that arrived with plate tectonics in the 1960s. The greatest reversal concerns chrysotile: the fibrous variety Collier's noted in passing is white asbestos, now classed as a human carcinogen and banned or restricted in more than sixty countries. Serpentinization is also studied as a source of hydrogen and methane, and the alkaline vents of the Lost City field, found in 2000, are discussed in origin-of-life research.
Written for this edition, 2026.