meteorite

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A stony or metallic mass of matter that has fallen to the earth's surface from outer space.

Century Dictionary and Cyclopedia

1. n. A mineral or metallic mass of extraterrestrial origin, or which, to use the common expression, has “fallen from the heavens.” Bodies of this kind were formerly often called aerolites, but meteorite is now their generally accepted name among scientific men. The fall of meteorites upon the earth is a by no means infrequent occurrence, and records of such events date back to many centuries before the present era. Traditions point to the very early use of meteoric iron for the manufacture of weapons; and it is also known that meteorites were not unfrequently the objects of worship in various parts of the world. In spite of this, the fall of rocks or metals from the heavens seemed to be so improbable an event that full credence was not given by scientific men to stories of such occurrences until about the beginning of the present century, when, several falls having taken place (at. Barbotan, France, 1790; Siena, 1794; Wold Cottage, Yorkshire, Eng., 1795; Salés, France, 1798; Benares, 1798; L'Aigle, France, 1803), the details of some of which were thoroughly investigated, a further denial of their genuineness became impossible. From the time of the fall at L'Aigle all doubt in the matter was abandoned. There are now several collections of meteorites, each of which contains specimens of between 300 and 400 different falls, and the whole number known is not far from 400, although it is by no means the case with all these occurrences that the specimens were seen to fall; many of them have been found on the earth's surface, but have been recognized as being extraterrestrial by their peculiar appearance and composition. The most important facts with regard to meteorites maybe concisely stated as follows: They have not been found to contain any element not known to occur on the earth; they have furnished no evidence of the existence of life on the body or bodies of which they originally formed a part; they bear no indications of having been formed in the presence of water, or of the existence of water beyond the earth's atmosphere in the regions from which they came; they do exhibit abundant evidence of having had what geologists would call an “igneous origin” they are never granitic in character, but resemble very closely certain volcanic rocks of not infrequent occurrence, with this difference, that in the case of the meteorites the iron associated with the silicated combinations exists in the metallic form, while in the terrestrial volcanic rocks it is, with rare exceptions, oxidized. Furthermore, meteorites, almost, without exception, show a certain family resemblance; so that it is necessary to admit, either that they all originally formed a part of one celestial body, or else that, having come from various members of the solar system, or from other systems, these have a wonderful resemblance to each other and to the earth itself. The most obvious division of meteorites is into metallie and stony, but the passage from one class to the other is by no means an abrupt one. All metallic meteorites agree in that the predominating metal is iron, with which nickel is almost invariably associated; indeed, it has not been proved that there is any meteoric iron entirely free from that metal. With the nickel cobalt is almost always found, as is the ease in terrestrial combinations. Tin and copper are also frequently found in meteorites in small quantity. The precious metals have not been detected in them. Meteorites composed almost entirely of metallic (niekeliferous) iron, forming a nearly homogeneous mass, have been denominated siderolites. These, however, almost always contain irregular nodular masses of pyrrhotite, schreibersite (phos-phuret of iron and nickel), either one or both. and occasionally of graphite. In a large proportion of the meteoric irons, etching the polished surface with an acid develops the so-called “Widmannstättian figures.” The development of these figures on the polished surface of a mass of iron found upon the earth's surface, and in regard to the time of whose fall nothing was known, was formerly considered to be sufficient evidence of the celestial origin of such a mass, especially if, in addition, the presence of nickel could be shown by chemical analysis. While most of the metallic masses thus referred have almost certainly been correctly classed among the meteorites, there may be cases in which such reference has not been justifiable, since it is now known that all celestial irons do not give the Widmannstattian figures, while the iron found in large quantity and over a wide area, associated with and embedded in basalt, near Ovifak in Greenland, contains nickel, and gives, when etched, figures which have generally been considered as Widmannstattian, although others have denied that they could properly be so denominated. The terrestrial origin of the Ovifak iron is, however, now generally admitted, although for a considerable time after its discovery this was not the case. The wide extent of the area over which this iron occurs, and its peculiarly intimate association with the minerals of which the basalt is made up, forbid the idea that the metal could have fallen from above into lava in process of eruption, which was at first the favorite theory of its origin. Next in order to the siderolites come the pallasites, so named from the fact that a large meteorite of this class was in 1772 discovered in Siberia by the distinguished traveler Pallas. Under the name of pallasiteare comprehended those meteorites which consist of a spongy or vesicular mass of iron, the cavities of which are in most cases partly or entirely filled with olivin, with which various other minerals are frequently associated, enstatite and bronzite being the most common, while chromite is of not infrequent occurrence. Both siderolites and pallasites belong to the class of metallic meteorites. By far the larger part of the stony meteorites are included under the designation of chondrites. In these the iron is distributed in fine particles through a more or less intimate mixture of silicates, with which chromite and magnetic pyrites are frequently associated, the silicates being chiefly olivin and bronzite. The name chondrite has reference to the fact that in this class of meteorites the material of which they are composed occurs in the form of rounded grains (chondri). The chondritic meteorites have, however, a quite varied structure, in some few cases passing into a breccia; they have been divided into numerous subgroups in accordance with these structural variations. Most of the stony meteorites contain iron disseminated through their mass in grains or nodules; but there are a few which are destitute of such metallic particles. There are also a few stony meteorites which do not exhibit any traces of a chondritic structure: the minerals of which these are made up do not, however, dilfer very essentially from those occurring in the chondrites. There are also a few very anomalous meteorites which contain carbonaceous matter associated with the stony chondritic material. This carbon is not graphitic, but is combined with hydrogen and oxygen, the product resembling to a certain extent that resulting from the decay of organic matter, but no traces of vegetable tissue have been discovered in these carbonaceous meteorites, which are only five or six in number. One or two interesting facts remain to be mentioned. The first is that since the phenomena of meteorites began to be observed and studied there have been extremely few falls of metallic meteorites. Of all the meteoric irons in the various collections, those of Hraschina in Austria (1751), of Dickson county, Tennessee (1855), of Braunau in Bohemia (1847), and a few others (in all probably about nine), are the only ones positively known to have fallen; all the others are considered meteoric on account of their peculiar appearance and chemical composition. The observed falls of stony meteorites, on the other hand, are numerous. Another remarkable fact is that all the meteorites which are known to have fallen are of inflnitesimally small size as compared with the earth. In the fall of L'Aigle some 2,000 to 3,000 stones were estimated to have reached the earth, and of these the largest weighed only seven or eight pounds. The largest meteorites of which the fall was observed are that of Ensisheim (1492), which weighed about 280 pounds, that of Juvinas (1821), 242 pounds, and that of Emmett county, Iowa (1879), when a considerable number of stones fell, the largest of them weighing 437 pounds. Some masses of iron believed to be meteorites, the date of whose fall is unknown, are much larger than this, but still utterly insignificant in size, not only as compared with the earth or its satellite, but even with the smallest celestial body of which anything is definitely known, namely the outer satellite of Mars, which has been estimated at from five to twenty-miles in diameter. The mass of iron on the river Bendegó in Brazil has been variously estimated at from seven to ten tons in weight; that of Tucuman (Campo del Cielo) is said to weigh fifteen tons. The Santa Caterina iron appears to be still larger, having been estimated at twentyfive tons; but doubts have been expressed as to whether this is really of celestial origin.
2. 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.

Wiktionary

1. n. A metallic or stony object or body that is the remains of a meteor

GNU Webster's 1913

1. n. (Min.) A mass of stone or iron which has fallen to the earth from space; an aërolite.

WordNet 3.0

1. n. stony or metallic object that is the remains of a meteoroid that has reached the earth's surface