Stony meteorites contain a variety of substances, but all are chemically distinguished from rocks formed on Earth. Arizona press, "Systematics and Evaluation of Meteorite Classification", "Analysis of iron meteorites, compiled and classified", https://en.wikipedia.org/w/index.php?title=Meteorite_classification&oldid=951704723, Creative Commons Attribution-ShareAlike License, CV-oxB chondrite (oxidized, Bali-like) subgroup, CH chondrite (Allan Hills 85085-like) group, Other chondrite groups, not in one of the major classes, K chondrite (Kakangari-like) grouplet (a grouplet is a provisional group with <5 members), This page was last edited on 18 April 2020, at 12:45. Image: Wikipedia, The Hoba iron meteorite is an example of an “Iron” being composed predominately of Fe, Ni metal. He describes his classification as based on Gustav Tschermak and Aristides Brezina with modifications by himself. More than 95% of meteorites observed to fall to Earth are stony. Stony-iron meteorites 3. Similarly classified meteorites may share a common origin, and therefore may come from the same astronomical object (such as a planet, asteroid, or moon) known as a parent body. The circular features in this image are known as chondrules and are thought to have formed as molten droplets in space early in solar system history. For example, most scientific information about the estimated age, chemical composition and history of the solar system is derived from meteoric evidence. Modern meteorite classification was worked out in the 1860s,[1] based on Gustav Rose's and Nevil Story Maskelyne's classifications. Meteorites that do not fit any known group (though they may fit somewhere within a higher level of classification) are ungrouped. These meteorites range in color and can be fine or coarse grained. In, Meteorites and the Early Solar System II, 19-52 (D.S. One group of chondrites (CB) has over 50% metal by volume and contains meteorites that were called stony irons until their affinities with chondrites were recognized. Some researchers hierarchize these terms, but there is no consensus as to which hierarchy is most appropriate. Iron meteorites cut in half exhibit a geometrical pattern known as a Widmanstatten pattern. Stony meteorites. Widmanstatten patterns occur because iron meteorites cooled under very high pressure over a long period of time. All types of meteorites record the pervasive effects of shock, derived from impact events of varying magnitude that have occurred throughout the history of the solar system. The iron meteorites are subdivided according to their structures as ataxites, hexahedrites and octahedrites. Stony-iron Meteorites. Stony meteorites, sometimes referred to as stone meteorites, fall to Earth more frequently than other types, but are more difficult to distinguish. [1], The first chemical classification was published by Oliver C. Farrington, 1907.[11]. Widmanstatten patterns occur because iron meteorites cooled under very high pressure over a long period of time. [10], Further modifications were made by Aristides Brezina. 1. [14] In 1923 he published a catalogue of the meteorites in the Natural History Museum (London). Stony-iron meteorites contain two subgroups: mesosiderites and pallasites. Stones are by far the most abundant meteorite type and are further subdivided into chondrites and achondrites, essentially on the basis of whether or not they contain mm-sized spherical objects known as chondrules. Iron meteorites are composed mostly of iron and also contain small amounts of nickel and cobalt. Three subgroups of iron meteorites, classified according to nickel content, are hexahedrites, octahedrites and ataxites. Iron meteorites are very heavy and are collected more frequently than other types of meteorites. [16], Weisberg et al. Scientists study meteorites to determine what the solar system is like. Stony Meteorites. There is no single, standardized terminology used in meteorite classification; however, commonly used terms for categories include types, classes, clans, groups, and subgroups. ALH 81005 is a lunar meteorite that was discovered in Antarctica. Representing 95% of meteorites to hit earth, stony meteorites are composed of over 75% rocky silicates (such as pyroxene, plagioclase, and olivine), with small amounts of metallic nickel and iron. Meteorites are to stones from other planets that survive the transition through the Earth's atmosphere. The iron meteorites were traditionally divided into objects with similar internal structures (octahedrites, hexahedrites, and ataxites), but these terms are now used for purely descriptive purposes and have given way to modern chemical groups. Stony–iron meteorites have always been divided into pallasites (which are now known to comprise several distinct groups) and mesosiderites (a textural term that is also synonymous with the name of a modern group). Meteorites that contain chondrules are known as chondrites. Rebekah Richards is a professional writer with work published in the "Atlanta Journal-Constitution," "Brandeis University Law Journal" and online at tolerance.org. (2006) scheme[5] meteorites groups are arranged as follows: where irons and stony–irons are considered to be achondrites or primitive achondrites, depending on the group. Meteorites are classified according to a variety of characteristics, especially mineralogical, petrological, chemical, and isotopic properties. Silicate masses that resemble Earth rocks. Image: Wikipedia. Lauretta and H.Y. Stony-iron meteorites represent a rare type of meteorite that contains both stone and iron. Both types are composed mostly of silicate minerals, but the great majority also contain metallic iron in small-scattered grains. It doesn’t contain chondrules and hence is an example of an achondrite. In the Krot et al. The Chelyabinsk meteorite is an example of a “Stone” in that it contains a significant amount of silicate material and only a small percentage of Fe, Ni metal. Meteorites are often divided into three overall categories based on whether they are dominantly composed of rocky material (stony meteorites), metallic material (iron meteorites), or mixtures (stony–iron meteorites). Meteorites can be subdivided into three groupings on the basis of how much silicate material compared to iron they contain: (1) Stones; (2) Stony-Irons and (3) Irons. Some iron meteorites also contain many silicate inclusions but are rarely described as stony irons. Meteorite classification may indicate that a "genetic" relationship exists between similar meteorite specimens. [15] A complete overview of his classification is given in the box below: Brian Harold Mason published a further revision in the 1960s. Gustav Rose worked on the meteorite collection of the Museum für Naturkunde, Berlin and Maskelyne on the collection of the British Museum, London. Iron meteorites 2. Most meteorites originate from collisions between two asteroids. (2006) Systematics and Evaluation of Meteorite Classification. Genuine meteorites for collectors and science available at Galactic Stone and Ironworks - www.galactic-stone.com. There are actually dozens of meteorite types, but those shown here are some of the most common or most popular. Types of meteorites: Classification of Meteorites Since the beginnings of the science of meteoritics in the late 18th century, several schemes have been developed to categorize the various meteorites in our collections. Mixtures of iron and stone. Below is a representation of how the meteorite groups fit into the more traditional classification hierarchy:{[1] }.
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