NWA 1235

Aubrite-anomalous
(possibly ungroupedModifying term used to describe meteorites that are mineralogically and/or chemically unique and defy classification into the group or sub-group they most closely resemble. Some examples include Ungrouped Achondrite (achondrite-ung), Ungrouped Chondrite (chondrite-ung), Ungrouped Iron (iron-ung), and Ungrouped Carbonaceous (C-ung). Click on Term to Read More)

Found 2000
no coordinates recorded

An 80 g weathered meteoriteWork in progress. A solid natural object reaching a planet’s surface from interplanetary space. Solid portion of a meteoroid that survives its fall to Earth, or some other body. Meteorites are classified as stony meteorites, iron meteorites, and stony-iron meteorites. These groups are further divided according to their mineralogy and Click on Term to Read More was found at a location in Northwest Africa and subsequently purchased by a private collector. The analysis of Northwest Africa 1235 was conducted at the Vernadsky Institute in Moscow, and it was determined that the dark brown fusion crustMelted exterior of a meteorite that forms when it passes through Earth’s atmosphere. Friction with the air will raise a meteorite’s surface temperature upwards of  4800 K (8180 °F) and will melt (ablate) the surface minerals and flow backwards over the surface as shown in the Lafayette meteorite photograph below. Click on Term to Read More and other features were consistent with a weathering grade of W2–W3 and that the meteorite had been shocked to stage S2/3 (Lorenz et al., 2003). The meteorite consists of 77 vol% essentially pure enstatiteA mineral that is composed of Mg-rich pyroxene, MgSiO3. It is the magnesium endmember of the pyroxene silicate mineral series - enstatite (MgSiO3) to ferrosilite (FeSiO3). Click on Term to Read More, with 8 vol% interstitialTerm applied to ions or atoms occupying sites between lattice points. Click on Term to Read More plagioclaseAlso referred to as the plagioclase feldspar series. Plagioclase is a common rock-forming series of feldspar minerals containing a continuous solid solution of calcium and sodium: (Na1-x,Cax)(Alx+1,Si1-x)Si2O8 where x = 0 to 1. The Ca-rich end-member is called anorthite (pure anorthite has formula: CaAl2Si2O8) and the Na-rich end-member is albite Click on Term to Read More. Enstatite contains micro-inclusions of glass, troiliteBrass colored non-magnetic mineral of iron sulfide, FeS, found in a variety of meteorites. Click on Term to Read More, FeNi-metal, silicaSilicon dioxide, SiO2., schreibersiteNi-Fe phosphide mineral, (Fe,Ni)3P, yellowish in color and predominantly found in iron and stony-iron meteorites. Schreibersite can also be found in a variety of other meteorites including some acapulcoites, aubrites, enstatite chondrites and achondrites, lunars, ureilites, winonaites and a smattering of other meteorite types like CM, CO and CB. Schreibersite Click on Term to Read More, niningerite, and a Mn-rich phase that might be a terrestrial decomposition product of alabanditeMagnesium sulfide found in aubrites and EL chondrites. Its formula is MnS. Click on Term to Read More.

The sulfides occur throughout the various phases and are predominantly Cr–Ti-bearing troilite (7 vol%). The low Ti content in troilite indicates that NWA 1235 experienced more oxidizingOxidation and reduction together are called redox (reduction and oxidation) and generally characterized by the transfer of electrons between chemical species, like molecules, atoms or ions, where one species undergoes oxidation, a loss of electrons,  while another species undergoes reduction, a gain of electrons. This transfer of electrons between reactants Click on Term to Read More conditions than all other enstatite meteorites. OldhamiteMn-Ca sulfide, (Mn,Ca)S, is a pale to dark brown accessory mineral found in minor amounts in highly reduced meteorites such as many enstatite chondrites, and some aubrites and enstatite achondrites. Oldhamite in enstatite chondrites likely formed by solar nebular gas condensation. CaS Oldhamite was also found in the most fresh Click on Term to Read More and sphalerite are also minor components, as well as sulfides of the FeS–MgS–MnS solid solutionCompositional variation resulting from the substitution of one ion or ionic compound for another ion or ionic compound in an isostructural material. This results in a mineral structure with specific atomic sites occupied by two or more ions or ionic groups in variable proportions. Solid solutions can be complete (with series. This sulfide solid solution normally serves as a reliable type indicator in E chondritesChondrites are the most common meteorites accounting for ~84% of falls. Chondrites are comprised mostly of Fe- and Mg-bearing silicate minerals (found in both chondrules and fine grained matrix), reduced Fe/Ni metal (found in various states like large blebs, small grains and/or even chondrule rims), and various refractory inclusions (such Click on Term to Read More: alabandite (MnS) occurs only in EL chondrites, while niningerite (MgS) is present only in EH chondrites. The sulfides from this solid solution series identified in NWA 1235 fallMeteorite seen to fall. Such meteorites are usually collected soon after falling and are not affected by terrestrial weathering (Weathering = 0). Beginning in 2014 (date needs confirmation), the NomComm adopted the use of the terms "probable fall" and "confirmed fall" to provide better insight into the meteorite's history. If Click on Term to Read More within a range intermediate between alabandite and niningerite, a range that was previously observed only in some EH melt rocks and in the EH7-anomalous meteorite Itqiy.

Si-bearing FeNi-metal constitutes 4.8 vol% of this meteorite, and is present mostly as mm-sized aggregates. These aggregates enclose prismatic enstatite (a common feature among E chondrites), schreibersite, troilite, and graphiteOpaque form of carbon (C) found in some iron and ordinary chondrites and in ureilite meteorites. Each C atom is bonded to three others in a plane composed of fused hexagonal rings, just like those in aromatic hydrocarbons. The two known forms of graphite, α (hexagonal) and β (rhombohedral), have Click on Term to Read More. Phlogopite, a rare F-bearing phyllosilicate associated with plagioclase, was identified in NWA 1235. This mineralInorganic substance that is (1) naturally occurring (but does not have a biologic or man-made origin) and formed by physical (not biological) forces with a (2) defined chemical composition of limited variation, has a (3) distinctive set of of physical properties including being a solid, and has a (4) homogeneous Click on Term to Read More is proposed to be a residual melt phase, and has previously been identified only in the EH melt rock Y-82189, and in the CV3 chondriteChondrites are the most common meteorites accounting for ~84% of falls. Chondrites are comprised mostly of Fe- and Mg-bearing silicate minerals (found in both chondrules and fine grained matrix), reduced Fe/Ni metal (found in various states like large blebs, small grains and/or even chondrule rims), and various refractory inclusions (such Click on Term to Read More Grosnaja; in Grosnaja it occurs as sodium phlogopite replacing Ca-rich minerals in chondrulesRoughly spherical aggregate of coarse crystals formed from the rapid cooling and solidification of a melt at  ~1400 ° C. Large numbers of chondrules are found in all chondrites except for the CI group of carbonaceous chondrites. Chondrules are typically 0.5-2 mm in diameter and are usually composed of olivine Click on Term to Read More and CAIsSub-millimeter to centimeter-sized amorphous objects found typically in carbonaceous chondrites and ranging in color from white to greyish white and even light pink. CAIs have occasionally been found in ordinary chondrites, such as the L3.00 chondrite, NWA 8276 (Sara Russell, 2016). CAIs are also known as refractory inclusions since they Click on Term to Read More.

The micro-inclusions (up to 20µm in size) of silica- and alkali-rich glass are ubiquitous in enstatite, with their shapes being controlled by the host enstatite crystal structureMutual arrangement of atoms, molecules or ions that are packed together in a crystal lattice to form a crystal. Click on Term to Read More. These glass inclusions have also been observed and extensively studied by Varela et al. (1998) in enstatites present in the Aubres and Norton County aubritesAubrites are named for the Aubres meteorite that fell in 1836 near Nyons, France. They are an evolved achondrite that is Ca-poor and composed mainly of enstatite (En100) and diopside (En50Wo50) with minor amounts of olivine (Fa0) and traces of plagioclase (An2-8).  They contain large white crystals of enstatite as Click on Term to Read More and the in the E-chondriteType of meteorite high in the mineral enstatite and also referred to as E-chondrites. Although they contain substantial amounts of Fe, it is in the form of Ni-Fe metal or sulfide rather than as oxides in silicates. Their highly reduced nature indicates that they formed in an area of the Click on Term to Read More (EL6/7; IMR) Happy Canyon, as well as in other meteorite and terrestrial sources. The existence of these glass inclusions in NWA 1235 is consistent with their hypothesis supporting an initial origin in the solar nebulaThe primitive gas and dust cloud around the Sun from which planetary materials formed. as a multi-phase precipitant from a fluid and/or vapor. Sometime thereafter, this pseudo-crystalline arrangement was affected by dehydration processes causing these ions to be exsolved and to form glass inclusions within crystallized enstatites, exhibiting variable glass/bubble ratios.

Although NWA 1235 is a reducedOxidation and reduction together are called redox (reduction and oxidation) and generally characterized by the transfer of electrons between chemical species, like molecules, atoms or ions, where one species undergoes oxidation, a loss of electrons,  while another species undergoes reduction, a gain of electrons. This transfer of electrons between reactants Click on Term to Read More achondriteAn achondrite is a type of stony meteorite whose precursor was of chondritic origin and experienced metamorphic and igneous processes. They have a planetary or differentiated asteroidal origin where the chondritic parent body reached a sufficient size that through heating due to radioactive decay of 26Al (aluminum isotope) and gravitational Click on Term to Read More with close similarities to other enstatite meteorites, it has many compositional features that are unique compared to the typical E chondrites and aubrites. It has a significantly higher abundance of FeNi-metal and a higher content of Si within this FeNi-metal compared to the aubrites; however, these abundances are similar to those of EL chondrites. NWA 1235 has a Ni/Co ratio that is distinct from all E chondrites and all aubrites except Mayo Belwa. Indications are that this is a unique achondrite which is genetically related to the enstatite meteorite clan. The photo of NWA 1235 shown above is a 1.05 g fusionProcess in which two lighter atomic nuclei combine to form a heavier atomic nucleus. Very high temperatures are normally required in order for atomic nuclei to collide with sufficient energy to overcome the Coulomb barrier (their mutual electrostatic repulsions). Fusion that occurs under high-temperature conditions is called thermonuclear fusion. Fusion Click on Term to Read More crusted partial slice.