One of two main types of Meteorite composed of roughly equal amounts by weight of silicate minerals and Ni-Fe metal. The stony-irons consist of two groups: mesosiderites and pallasites. However, there is gradual shading into metal-rich stony meteorites such as the lodranites (once considered stony-irons) and silicate-rich iron meteorites. Stony-iron meteorites are less abundant than their, the other being pallasites. Mesosiderites are a mixture of approximately 50% basaltic, gabbroic and orthopyroxenitic silicates and 50% Ni-Fe Element that readily forms cations and has metallic bonds; sometimes said to be similar to a cation in a cloud of electrons. The metals are one of the three groups of elements as distinguished by their ionization and bonding properties, along with the metalloids and nonmetals. A diagonal line drawn and sulfides. The name derives from the Greek “mesos” meaning “middle” or “half” and “sideros” for “iron;” hence “half-iron”. The silicates are heavily brecciated igneous rocks, similar to Most common type of achondrite meteorite and a member of the HED group. Eucrites are basalts composed primarily of pigeonite and anorthite (An60-98). Eucrites have been placed into three subgroups based on mineralogical and chemical differences. • Non-cumulate eucrites represent the upper crust that solidified on a magma ocean after, Diogenites belong to the evolved achondrite HED group that also includes howardites and eucrites. They are named after the Greek philosopher Diogenes of Apollonia, of the 5th century BCE, who was the first to suggest that meteorites come from outer space (a realization forgotten for over 2,000 years). They are, and clearly came from the Outermost layer of a differentiated planet, asteroid or moon, usually consisting of silicate rock and extending no more than 10s of km from the surface. The term is also applied to icy bodies, in which case it is composed of ices, frozen gases, and accumulated meteoritic material. On Earth, the of an achondritic The body from which a meteorite or meteoroid was derived prior to its ejection. Some parent bodies were destroyed early in the formation of our Solar System, while others like the asteroid 4-Vesta and Mars are still observable today.. The metal in mesosiderites is similar to that of IIIAB irons, and came from the In the context of planetary formation, the core is the central region of a large differentiated asteroid, planet or moon and made up of denser materials than the surrounding mantle and crust. For example, the cores of the Earth, the terrestrial planets and differentiated asteroids are rich in metallic iron-nickel. of a differentiated asteroid, genetically unrelated to the precursor of the eucritic and diogenitic portion. Mesosiderites have no mantle-like material at all. This odd combination of crustal and core material can be explained (though still debated) by a collision of two differentiated asteroids in which the still-liquid core of one asteroid mixed with the solidified crust of the other. This model requires collisional disruption followed by gravitational reassembly of at least one of the asteroids.
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