serpentine

1. Of or resembling a serpent, as in form or movement; sinuous.
2. Subtly sly and tempting.

[Middle English, from Old French serpentin, from Late Latin serpentīnus, from Latin serpēns, serpent-, serpent. See serpent.]

The name traditionally applied to three hydrated magnesium silicate minerals, antigorite, chrysotile, and lizardite. All have similar chemical compositions but with three different but closely related layered crystal structures. Serpentine also has been used as a group name for minerals with the same layered structures but with a variety of compositions. The general formula is M₃T₂O₅(OH)₄, where M may be magnesium (Mg), ferrous iron (Fe²⁺), ferric iron (Fe³⁺), aluminum (Al), nickel (Ni), manganese (Mn), cobalt (Co), chromium (Cr), zinc (Zn), or lithium (Li); and T may be silicon (Si), Al, Fe³⁺, or boron (B).

Lizardite has a planar structure, with the misfit accommodated by slight adjustments of the atomic positions within the layers. Chrysotile has a cylindrical structure in which the layers are either concentrically or spirally rolled to produce fiber commonly ranging from 15 to 30 nanometers in diameter, and micrometers to centimeters in length. These fibers have great strength and flexibility and are the most abundant and commonly used form of asbestos. Antigorite has a modulated wave structure, with wavelengths generally varying between 3 and 5 nm. See also Asbestos.

adjective

Repeatedly curving in alternate directions: anfractuous, flexuous, meandrous, sinuous, snaky, tortuous, winding. See repetition, straight/bent.

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A group of minerals consisting of hydrous magnesium silicate, or rock largely composed of these minerals; commonly occurs in greenish shades; used for decorative stone; the prominent constituent in some commercial marbles.

Environment

A secondary mineral, resulting from non-simple hydrothermal alteration of magnesium silicates. Serpentinizing solutions tend to be very pervasive, attacking any rock in the area, so we find alterations and coatings on quite unrelated species, such as quartz crystals.

Crystals unknown, except as the parallel fibers called chrysotile asbestos. Also massive, sometimes with a botryoidal surface as if it had been amorphous when formed.

White, green, brown, yellow, red, black. Luster silky, waxy to greasy; hardness 2-5; specific gravity 2.2-2.6; cleavage none to fibrous. Reasonably compact to flaky and slickensided; translucent to opaque; yellowish varieties often fluorescent cream-yellow.

Alkaline magnesium silicate (43.O% MgO, 44.1% SiO ₂ , 12.9% H ₂ O, plus some iron and possibly nickel).

Infusible, but tends to decrepitate (fly apart) very badly. Light-colored material blackens, gives water, and then lightens in closed tube. Decomposed by hydrochloric acid, the freed silica separating as gel.

Both a rock and a mineral. A very common mineral in regions of metamorphism (see also in the rock section). Always suspect it in a rock with a greasy feel. Usually relatively soft and dark greenish. White varieties are not common and typically are associated with other serpentines. The serpentine asbestos (chrysotile) varieties are softer and more flexible than the amphibole asbestoses. The blackening and the water released in the closed tube also distinguish it from amphibole asbestos. Ease with which the green massive material can be scratched distinguishes it from nephrite jade; it is harder than chlorite, however.

Since serpentine seems frequently to form by the alteration of primary magnesium silicates taking up the water originally present in the magma, they are found wherever dark-colored magnesium silicate rocks occur. Great serpentine formations, as in the California Coast Ranges, give it rock status as well as mineralogical identity. Readily identifiable in highway cuts by the shiny, concave-convex greenish, slickensided surfaces.

Serpentinization seems commonly to invade mineralized areas, altering quite unrelated minerals to serpentine. In this way we find at the famous Tilly Foster Mine (Brewster, New York) that serpentine is pseudomorphous after numerous minerals, and also forms botryoidal coatings and films ranging from white to black. Large masses of serpentine result from the alteration of the dark intrusives, as at Hoboken, New Jersey; Staten I., New York; Eden Mills, Vermont; Thetford and Asbestos, Quebec. Veins of fibrous asbestos cut through such bodies; there are quarries or mines for chrysotile asbestos in those regions near Coalinga, California, and in Arizona.

Chrysotile is considered the safer asbestos (crocidolite, a bluish amphibole, is the alternative). Serpentine marbles make the popular verd antique (dark green with white calcite veins). Closely related nickel-bearing serpentines are important ores of that metal (garnierite) and are mined in New Caledonia. Closely resembling nephrite jade and commonly used in decorative Chinese carvings. Nephrite boulders are associated with serpentine and may be a result of metamorphic creation of excessively hot knots, dehydrated into nephrite.

For other uses, see Serpentine (disambiguation).

Serpentine

Dish of serpentine with inlaid gold fish, 1st century BCE or CE, with 9th century mounts

Necklace and earring set made from semiprecious stones. The circular green beads are Russian serpentine. Also used are jasper (red) and fluorite (blue).

The serpentine group describes a group of common rock-forming hydrous magnesium iron phyllosilicate ((Mg, Fe)₃Si₂O₅(OH)₄) minerals; they may contain minor amounts of other elements including chromium, manganese, cobalt and nickel. In mineralogy and gemology, serpentine may refer to any of 20 varieties belonging to the serpentine group. Owing to admixture, these varieties are not always easy to individualize, and distinctions are not usually made. There are three important mineral polymorphs of serpentine: antigorite, chrysotile and lizardite.

Many types of serpentine have been used for jewellery and hardstone carving.

Contents 1 Overview 2 Antigorite 3 Lizardite 4 State Emblem 5 See also 6 References

Overview

"Their olive green color and smooth or scaly appearance is the basis of the name from the Latin serpentinus, meaning serpent rock," according to Best (2003). They have their origins in metamorphic alterations of peridotite and pyroxene. Serpentines may also pseudomorphously replace other magnesium silicates. Alterations may be incomplete, causing physical properties of serpentines to vary widely. Where they form a significant part of the land surface, the soil is unusually high in clay.

Antigorite is the polymorph of serpentine that most commonly forms during metamorphism of wet ultramafic rocks and is stable at the highest temperatures—to over 600°C at depths of 60 km or so. In contrast, lizardite and chrysotile typically form near the Earth's surface and break down at relatively low temperatures, probably well below 400°C. It has been suggested that chrysotile is never stable relative to either of the other two serpentine polymorphs.

Samples of the oceanic crust and uppermost mantle from ocean basins document that ultramafic rocks there commonly contain abundant serpentine. Antigorite contains water in its structure, about 13 percent by weight. Hence, antigorite may play an important role in the transport of water into the earth in subduction zones and in the subsequent release of water to create magmas in island arcs, and some of the water may be carried to yet greater depths.

Soils derived from serpentine are toxic to many plants, because of high levels of nickel, chromium, and cobalt; growth of many plants is also inhibited by low levels of potassium and phosphorus and a low ratio of calcium/magnesium. The flora is generally very distinctive, with specialised, slow-growing species. Areas of serpentine-derived soil will show as strips of shrubland and open, scattered small trees (often conifers) within otherwise forested areas; these areas are called serpentine barrens.

Most serpentines are opaque to translucent, light (specific gravity between 2.2–2.9), soft (hardness 2.5–4), infusible and susceptible to acids. All are microcrystalline and massive in habit, never being found as single crystals. Luster may be vitreous, greasy or silky. Colours range from white to grey, yellow to green, and brown to black, and are often splotchy or veined. Many are intergrown with other minerals, such as calcite and dolomite. Occurrence is worldwide; New Caledonia, Canada (Quebec), USA (northern California), Afghanistan, Cornwall, China, Asia, France, Norway and Italy are notable localities.

Rock composed primarily of these minerals is called serpentinite. Serpentines find use in industry for a number of purposes, such as railway ballasts, building materials, and the asbestiform types find use as thermal and electrical insulation (chrysotile asbestos). The asbestos content can be released to the air when serpentine is excavated and if it is used as a road surface, forming a long term health hazard by breathing. Asbestos from serpentine can also appear at low levels in water supplies through normal weathering processes, but there is as yet no identified health hazard associated with use or ingestion. In its natural state, some forms of serpentine react with carbon dioxide and re-release oxygen into the atmosphere.

The more attractive and durable varieties (all of antigorite) are termed "noble" or "precious" serpentine and are used extensively as gems and in ornamental carvings. Often dyed, they may imitate jade. Misleading synonyms for this material include "Korean jade", "Suzhou jade", "Styrian jade", and "New jade". New Caledonian serpentine is particularly rich in nickel, and is the source of most of the world's nickel ore.

Polished slab of bowenite serpentine, a variety of antigorite. Typical cloudy patches and veining are apparent.

The Māori of New Zealand once carved beautiful objects from local serpentine, which they called tangiwai, meaning "tears". Material quarried in Afghanistan, known as sang-i-yashm, has been used for generations. It is easily carved, taking a good polish, and is said to have a pleasingly greasy feel.

The lapis atracius of the Romans, now known as verde antique, or verde antico, is a serpentinite breccia popular as a decorative facing stone. In classical times it was mined at Casambala, Thessaly, Greece. Serpentinite marbles are also widely used: Green Connemara marble (or Irish green marble) from Connemara, Ireland (and many other sources), and red Rosso di Levanto marble from Italy. Use is limited to indoor settings as serpentinites do not weather well.

Antigorite

Lamellated antigorite occurs in tough, pleated masses. It is usually dark green in colour, but may also be yellowish, gray, brown or black. It has a hardness of 3.5–4 and its lustre is greasy. The monoclinic crystals show micaceous cleavage and fuse with difficulty. Antigorite is named after its type locality, the Valle di Antigorio in Italy.

Bowenite is an especially hard serpentine (5.5) of a light to dark apple green colour, often mottled with cloudy white patches and darker veining. It is the serpentine most frequently encountered in carving and jewellery. The name retinalite is sometimes applied to yellow bowenite. The New Zealand material is called tangiwai.

Although not an official species, bowenite is the state mineral of Rhode Island: this is also the variety's type locality. A bowenite cabochon featured as part of the "Our Mineral Heritage Brooch", was presented to First Lady Mrs. Lady Bird Johnson in 1967.

Williamsite is a local varietal name for antigorite that is oil-green with black crystals of chromite or magnetite often included. Somewhat resembling fine jade, williamsite is cut into cabochons and beads. It is found mainly in Maryland and Pennsylvania, USA.^[1]

Lizardite

Polished serpentine, from the Val d'Aosta, sold as Gressoney. Used at the United Nations building in New York.

Extremely fine-grained, scaly lizardite (also called orthoantigorite) comprises much of the serpentine present in serpentine marbles. It is triclinic, has one direction of perfect cleavage, and may be white, yellow or green. Lizardite is translucent, soft (hardness 2.5) and has an average specific gravity of 2.57. It can be pseudomorphous after enstatite, olivine or pyroxene, in which case the name bastite is sometimes applied. Bastite may have a silky lustre.

Lizardite is named after its type locality on the Lizard Peninsula, Cornwall, UK.^[2] It is worked by local artisans into various trinkets which are sold to tourists.

State Emblem

In 1965 the California Legislature designated serpentine (the mineral) as “the official State Rock and lithologic emblem.”^[3]

See also

• Serpentine soil
• Serpentinite

References

Wikimedia Commons has media related to: Serpentine

Wikisource has the text of a 1911 Encyclopædia Britannica article about Serpentine.

1. ^ http://www.cst.cmich.edu/users/dietr1rv/serpentine.htm Gemrocks, R. V. Dietrich, 2005
2. ^ Lizardite: Lizardite mineral information and data
3. ^ California Government Code § 425.2; see http://www.leginfo.ca.gov/cgi-bin/displaycode?section=gov&group=00001-01000&file=420-429.8

• R. V. Dietrich - Gemrocks
• Mineral description from Mineral galleries
• Best, Myron G. (2003), Igneous and Metamorphic Petrology, 2nd edition. Blackwell Publishing. ISBN 1-40510-588-7
• Kruckeberg, Arthur R. (2002) Geology and Plant Life: the Effects of Landforms and Rock Types on Plants. Seattle: University of Washington Press. ISBN 0-295-98452-X
• Evans, Bernard W. (2004), The Serpentinite Multisystem Revisited: Chrysotile is Metastable. In: International Geology Review, v. 46, pages 479-506
• Hoskins, W. G. (1976) One Man's England. Chap. 7: Cornwall, pp. 73. London: BBC

v • d • e Phyllosilicates Serpentine group Antigorite · Chrysotile · Lizardite Clay mineral group Chlorite1 · Dickite · Halloysite · Illite · Ilmenite · Kaolinite · Montmorillonite · Nacrite · Nontronite · Palygorskite · Saponite · Sepiolite · Serpentine1 · Talc Mica group Biotite · Glauconite · Lepidolite · Margarite · Muscovite · Phlogopite Chlorite group Chlorite 1. Serpentine and Chlorite are sometimes considered clay minerals

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Dansk (Danish)
1.
adj. - slangeagtig, slangebugtet
n. - snoet sti, skøjtefigur bestående af tre sammenhængende cirkler
v. intr. - sno sig, slange sig

2.
n. - serpentin

Nederlands (Dutch)
kronkelend, slangachtig, kronkelen, serpentine

Français (French)
1.
adj. - sinueux
n. - système de verrouillage d'une mèche (d'un arquebusier), canon de différents calibres, figure (de patinage artistique)
v. intr. - serpenter

2.
n. - (Minér) serpentine

Deutsch (German)
1.
adj. - Serpentinen-, Schlangen-, schlangengleich
n. - Schlangenbogen
v. - sich schlängeln

2.
n. - Serpentin

Ελληνική (Greek)
adj. - οφιοειδής, ελικοειδής, ύπουλος, προδοτικός
n. - (ορυκτολ.) οφίτης, σερπεντίνης, φιγούρα του πατινάζ
v. - κινούμαι ελικοειδώς

Italiano (Italian)
serpentino, serpentina, serpeggiare

Português (Portuguese)
adj. - sinuoso, pérfido
n. - serpentina (f)
v. - serpear

Русский (Russian)
серпантин, змеевик, извилистая дорога, серпантин, змеиный, змеевидный, извилистый, подобный змею-искусителю, дьявольский, передвигаться подобно змее, заставлять извиваться

Español (Spanish)
1.
adj. - serpentino, astuto, sinuoso, tortuoso
n. - serpentina, serpentina (figura de patinaje), serpentín
v. intr. - serpentear, andar sin rumbo

2.
n. - serpentina

Svenska (Swedish)
adj. - ormliknande, slingrande
n. - serpentin
v. - slingra sig, orma sig

中文（简体）(Chinese (Simplified))
1. 蛇的, 阴险的, 层层卷绕的, 蛇纹石, 像蛇般行进

2. 古时大炮的一种

中文（繁體）(Chinese (Traditional))
1.
n. - 古時大炮的一種

2.
adj. - 蛇的, 陰險的, 層層捲繞的
n. - 蛇紋石
v. intr. - 像蛇般行進

한국어 (Korean)
1.
adj. - 뱀 모양의, 꾸불꾸불한, 남을 모함하는
n. - 뱀 모양의 것, 사문석, 옛날 대포의 일종
v. intr. - 꾸불꾸불 구부러지다, 굽이치다, 비틀거리며 걷다

2.
n. - 함수의 마그네슘 규산염

日本語 (Japanese)
adj. - 蛇のような, 曲がりくねった, 陰険な

العربيه (Arabic)
‏(صفه) ملتف, شيطاني (الاسم) حجر ألحيه " حجر أخضر اللون مرقط أحيانا كجلد الحيه " (فعل) يمشي بتموج‏

עברית (Hebrew)
adj. - ‮נחשי, מתפתל, ערמומי, בוגדני‬
n. - ‮עיקול בדרך, תותח בקוטר מסוים, חלק בבריח של רובה ישן להחזקת הגפרור, צורה של שלושה מעגלים בשורה אחת שנוצרה ע"י החלקה על השלג‬
v. intr. - ‮נע בעיקולים‬
n. - ‮אבן סיליקאט של מגנזיום בצבע ירוק המשמשת לאחר ליטוש לקישוט‬

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