from The American Heritage® Dictionary of the English Language, 4th Edition
- n. A stony or metallic mass of matter that has fallen to the earth's surface from outer space.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. A metallic or stony object or body that is the remains of a meteor
from the GNU version of the Collaborative International Dictionary of English
- n. A mass of stone or iron which has fallen to the earth from space; an aërolite.
from The Century Dictionary and Cyclopedia
- n. A mineral or metallic mass of extraterrestrial origin, or which, to use the common expression, has “fallen from the heavens.”
- n. The great interest in meteorites in recent years has led not only to a minuter study of known meteorites, but also to a keener search for new specimens and a closer watch for falls. The result of this activity is shown in the very considerable increase in the number of known meteorites from well-authenticated independent sources. The collections of Vienna and London contain each between 550 and 600 specimens and the Ward-Coonley collection (now in Now York) has over 600. Of recent discoveries of meteoric iron, the Willamette specimen, found in Clackamas county, Oregon, in 1902, is remarkable for its great size (being one of the four largest masses known to exist: see below), and also for various structural features. Its dimensions are 10¼ × 7 × 4 feet, and its estimated weight about 15½ tons. The form (see cut) is roughly conical, and the cone-shaped portion, lying beneath when found, was obviously the front side (brustseite) in the forward motion of the mass. A remarkable feature of this iron is the large, basin-like cavities on the upper exposed surface, probably the result of terrestrial decomposition during the long period that has elapsed since its fall. Near Cañon Diablo, Arizona, in a very limited area, more than 600 masses of meteoric iron have been found since 1891. They vary from about 1,200 pounds to half an ounce and less in weight and their occurrence is immediately associated with a remarkable crater (¾ of a mile wide, 500 feet deep), which is believed to owe its origin to the impact of the meteoric mass. This iron is noteworthy because it has been shown by various investigators, especially by Moissan of Paris, to contain minute transparent octahedrons of diamond. It has also yielded green hexagonal crystals of carbon silicide (moissanite), identical with the artificial compound used in the arts as an abrasive under the name of carborundum. The mass of meteoric iron, the ‘Ahnighito meteorite,’ brought to New York by Lieutenant Peary from, Cape York, Greenland, in 1897 (known since 1818), is unquestionably the largest meteorite preserved in any museum and perhaps the largest mass known to exist. It measures 11 × 7½ × 5½ feet and weighs 36½ tons; its form is shown in the cut. A somewhat higher weight (estimated as 46 tons) is given for the iron of Bacubirito, Sinaloa, Mexico (known since 1871), while that of Chupadero, Chihuahua, Mexico (1852), weighs about 16 tons. The meteoric origin of the Ahnighito iron is well established, although the iron of Disko Island and those of some other localities on the west coast of Greenland are certainly terrestrial. The great mass of Santa Catharina, Brazil, remarkable for its high percentage of nickel (34 per cent.), is now generally regarded as terrestrial; this type is called catarinite by Meunier. Some doubt also has been cast upon the meteoric origin of the iron from Oktibbeha county, Mississippi, which contains 60 per cent. of nickel (oktibbehite type, Meunier). The meteorites which have been seen to fall between 1890 and 1906 number about 30. These include three irons, those of Quesa, Spain (1898), of Bugaldi, New South Wales (1900), and of Ngoureyma, in Northwest Africa (1900); the latter-named mass weighed 37½ kilograms, and its remarkable appearance is shown in the adjoining cut. The minute microscopic and chemical examination of meteoric irons has led to more definite knowledge of the composition of the various iron-nickel alloys, kamacite, tænite, and plessite forming the triad (or trias) of Reichenbach (see Widmannstättian figures, under Widmannstättian); of these, kamacite contains from 4.8 to 7.4 per cent. of nickel, tænite from 16.7 to 38.1 per cent., and plessite is regarded as a eutectic mixture of the two species. Reichenbach's lamprite (glanzeisen) has been shown, however, to be not nickel-iron, but in part iron carbide (including cohenite (Fe, Ni)3C), and in part schreibersite. The edmondsonite of Flight (meteorin of Abel) is only tænite. The wickelkamacite of Brezina (hülleisen of Reichenbach) is kamacite, not in regular form as usual, but of irregular outline inclosing accessory constituents, sulphids, graphite, silicates, etc. The iron sulphid of meteoric irons is now conceded to be troilite (FeS), not pyrrhotine (Fe7S8). The list of chemical elements identified in meteorites has been increased by the following, several of them detected in traces only and a few perhaps needing confirmation: gold, silver, platinum, iridium, palladium, lead, gallium, selenium; the stone of Saline township, Kansas, contains free phosphorus. The identification of leucite, a mineral of rather rare occurrence in terrestrial igneous rocks, as an essential constituent of the meteoric stone of Schafstädt is an interesting point; it is probably also present in the Pavlovka stone (1882). The classification of meteorites now generally adopted is essentially that of Gustav Rose (Berlin, 1863) as extended and elaborated by later writers, particularly A. Brezina of Vienna. The fundamental division is that between the meteoric irons, or siderites, consisting essentially of metallic iron (probably in all cases nickel-iron), and the meteoric stones, or aërolites, in which silicates predominate, the metallic nickel-iron sometimes (though rarely) entirely absent. As a transition-group between the irons and stones belong those meteorites in which the iron forms a continuous, sponge-like mass inclosing silicates (chiefly olivin and bronzite); these are often embraced under the general name of siderolites, and sometimes (as below, Brezina) divided into siderolites and lithosiderites, according as the iron, on a cross-section, appears as separate grains or forms a continuous web. The system of Brezina (catalogue of the Ward-Coonley collection, 1904) recognizes further the following prominent divisions: I. Stones: achondrites, chondri generally absent, metallic iron absent or only sparingly present; chondrites, chondri prominent, bronzite, olivin, and iron essential; chondrites, with enstatite, anorthite, and iron essential; siderolites, iron inclosing silicates, iron in separate grains in section. II. Irons: tithosiderites, iron and silicates, the iron continuous in section; octahedrites, irons with octahedral structure as shown in Widmannstättian figures; hexahedrites, irons with cubic structure and cleavage; ataxites, structure interrupted or indistinct. These divisions are further separated into groups or types briefly characterized as follows: Achondrites: chladnite (abbreviated Chl), consisting chiefly of bronzite (named, like the mineral chladnite (= enstatite), after the physicist Chladni (1756–1827), who wrote about meteors); chladnite with bronzite, black or metallic veined (Chla); angrite (A), chiefly augite (named after the meteorite of Angra dos Reys, Brazil; date of fall, 1869); chassignite (Cha), chiefly olivin (Chassigny, France, 1815); bustite (Bu), bronzite and augite (Busti, India, 1852); amphoterite (Am), bronzite and olivin (named by Tschermak); rodite (Ro), bronzite and olivin, brecciated or breccia-like (La Roda, Spain, 1871); eucrite (Eu), augite with anorthite (named by Rose in 1863; also used for a terrestrial rock: see eucrite); shergottite (She), augite with maskelynite (Sherghotty, India, 1865); (10) howardite (Ho), bronzite, olivin, augite, and anorthite (named by Rose after Edward Howard, who first determined the true nature of meteoric iron: Philos. Trans. Roy. Soc, 1802); (11) howardite, brecciated (Hob); (12) leucituranolite (L), leucite, anorthite, augite, and glass (named by C. Klein, 1904). Chondrites: howarditic chondrite (Cho); the same, veined (Choa); chondrite, white and friable (Cw); the same, veined (Cwa); the same, brecciated (Cwb); intermediate chondrite (Ci), firm, with white and gray chondri; the same, veined (Cia); the same, brecciated (Cib); gray chondrite (Cg), firm gray mass with chondri; (10) the same, veined (Cga); (11) the same, brecciated (Cgb); (12) orvinite (Co), black, infiltrated mass, discontinuous crust (Orvinio, Italy, 1872); (13) tadjerite (Ct), black, semiglassy, without crust (Tadjéra, Africa, 1867); (14) black chondrite (Cs), dark or black mass; chondri of various colors; (15) the same, veined(Csa); (16) ureilite (U), black mass, chondritic or granular, iron in veins, etc. (Novo Urei, Russia, 1886); (17) carbonaceous chondrite (K), dull-black friable chondri with free carbon and little or no iron; (18) the same, spherulitic (Kc); (19) the same, spherulitic, veined (Kca); (20) spherulitic chondrite (Cc), mass friable, chondri not breaking with matrix; (21) the same, veined (Cca); (22) the same, brecciated (Ccb); (23) ornansite (Cco), friable mass of chondri (Ornans, France, 1868); (24) ngawite (Ccn), friable, brecciated mass of chondri (Ngawi, Java, 1883); (25) spherulitic chondrite, crystalline (Cck); (26) the same, veined (Ccka): (27) the same, brecciated (Cckb); (28) crystalline chondrite (Ck); (29) the same, veined (Cka); (30) the same, brecciated (Ckb). Enstatite-anorthite chondrites: crystalline chondrite (Cck), enstatite, anorthite, and iron with round chondri. Siderolites: mesosiderite. (M), sponge-like mass of iron inclosing crystalline olivin and bronzite (name given by G. Rose, 1862: see mesosiderite); grahamite (Mg), the same, with also plagioclase (J. Lorimer Graham of New York city); lodhranite (Lo), granular crystalline olivin and bronzite in iron (Lodhran, India, 1868) Lithosiderites: siderophyre (S), bronzite grains with accessory asmanite in iron (named by Tschermak); – groups of pallasites, iron inclosing olivin (Pk), (Pr), (Pi), (Pa), differing chiefly in relation to the olivin (named from Pallas iron, Krasnoyarsk, Siberia, 1749). Octahedrites: groups –, fine octahedrites (Off), (Ofv), (Of), showing thin lamellæ of varying types, widths 0.3–0.4 millimeters; medium octahedrite (Om), lamellæ 0.5–0.10 millimeters; broad octahedrite (Og), lamellæ 1.5–2.0 millimeters; broadest octahedrite (Ogg); –(11) brecciated octahedrites, fine, medium, etc., different types (Obk), (Obn), (Obz), (Obzg), (Obc); (12) octahedrite, Hammond group (Oh), Hexahedrites: normal, not granular (H); granular (Ha); brecciated (Hb). Ataxites: groups (respectively designated as Dc, Dsh, Db, Dl, Dn, Ds, Dp, and Dm), differing chiefly either in amount of nickel or in structure; the Siratic group (Ds, and named from a place in Senegal) is poor in nickel, but contains rhabdite. Daubrée divided all meteorites into four grand divisions, according to the amount of iron present, namely: holosiderites, containing no silicates; syssiderites, an iron mass inclosing silicates; sporadosiderites, stones with disseminated grains of iron; asiderites, stones containing no metallic iron. He further divided the sporadosiderites into polysiderites, iron abundant; oligosiderites, iron less abundant; and cryptosiderites, iron not visible to the eye. This classification was further developed by Meunier, who distinguished fifty-three groups, named in most cases after some typical meteorite; these begin with the highly nickeliferous irons oktibbehite and catarinite (see above), also tazewellite, nelsonite, braunite, etc., and end with orgueilite and bokkewellite.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. stony or metallic object that is the remains of a meteoroid that has reached the earth's surface
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