Fell June 28, 1861
43° 40′ N., 45° 23′ E. A shower of stones fell after sonic booms at 7:00 P.M. in Grosnaja, Mekensk, USSR. Only one stone of about 3.5 kg was recovered, the remainder falling into the river Terek. It has been shocked to stage S3. The CV3 group was subdivided into the following three subgroups (McSween, 1977; Weisberg et al., 1997):
- Oxidation 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 subgroup: e.g., Arch, Efremovka, Leoville, Vigarano, and QUE 93429
- Oxidized-Allende subgroup: e.g., Allende, Axtell, Tibooburra, and ALH 84028
- Oxidized-Bali subgroup: e.g., Bali, Grosnaja, Kaba, and Mokoia
The CV-oxidized and CV-reduced subgroups are separated on the basis of 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 abundances and the Ni content of sulfide (Howard et al., 2010). The previously used discriminator, Fe oxide, Fe2+Fe3+2O4, containing oxidized iron (Fe3+) found in the matrix of carbonaceous chondrites and as diagnostic component in CK chondrites. In CK chondrites, magnetite is typically chromian, containing several wt. % Cr2O3. abundance, has been shown to overlap between Oxidation 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 and reduced subgroups. The oxidized-Bali subgroup has a higher degree of aqueous alteration than oxidized-Allende. The subgroups reflect varying degrees of aqueous/oxidative alteration, which has been found to be correlated with the amount of ice-bearing Fine grained primary and silicate-rich material in chondrites that surrounds chondrules, refractory inclusions (like CAIs), breccia clasts and other constituents. that was initially accreted (Ebel et al., 2009). For more mineralogical relationships, see Appendix I, Carbonaceous Chondrites).Some investigators (e.g., Greenwood et al., 2003 and Wasson et al., 2013) have proposed that the CK Chondrites 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 could represent an extension of the CV group. This subgroup is considered to reflect varying degrees of metamorphism including impact-generated crushing, thermal alteration, and recrystallization processes (Wasson et al., 2013). In a subsequent study, Dunn et al. (2016) compared magnetite in a number of CK and Meteorite class named after the Vigarano meteorite that fell in Italy in 1910. They have abundant large, well-defined rimless (?) chondrules of magnesium-rich olivine (~0.7 mm diameter; 40-65 vol. %), often surrounded by iron sulfide. They also contain 7-20 vol. % CAIs. The often dark-gray matrix is dominated by Fe-rich, and presented geochemical, mineralogical, and petrographic evidence which is more consistent with separate CV and CK parent bodies; details of their study can also be found on the Dhofar 015 page. A study was undertaken by Bonal et al. (2004, 2006) to refine the subtypes of several CV3 chondrites. They utilized several methods to obtain their data, including Raman spectrometry of Pertaining to C-containing compounds. Organic compounds can be formed by both biological and non-biological (abiotic) processes. material, a petrologic study of Fe zoning in Group of silicate minerals, (Mg,Fe)2SiO4, with the compositional endpoints of forsterite (Mg2SiO4) and fayalite (Fe2SiO4). Olivine is commonly found in all chondrites within both the matrix and chondrules, achondrites including most primitive achondrites and some evolved achondrites, in pallasites as large yellow-green crystals (brown when terrestrialized), in the silicate portion phenocrysts, presolar grain abundance, and a Element occurring in the right-most column of the periodic table; also called "inert" gases. In these gases, the outer electron shell is completely filled, making them very unreactive. study. These methods are in contrast to that of TL sensitivity data of An alumino-silicate mineral containing a solid solution of calcium, sodium and potassium. Over half the Earth’s crust is composed of feldspars and due to their abundance, feldspars are used in the classification of igneous rocks. A more complete explanation can be found on the feldspar group page. which is typically used to determine subtypes of ordinary chondrites, and which was previously applied to the CV3 chondrites. They suggest that TL sensitivity data are not applicable to aqueously altered carbonaceous chondrites because of loss of feldspars through dissolution, leading to an underestimate of the petrologic subtypes. They have redefined the petrologic subtypes of the common CV3 members as follows:
These differences in petrologic subtype are explained by Greenwood et al. (2009) in their study of CV and Class of carbonaceous chondrite named for the Karoonda meteorite that fell in Australia in 1930. They are more oxidized than all other carbonaceous chondrites and genetically distinct from CV chondrites. CK chondrites appear dark-gray or black due to a high percentage of Cr-rich magnetite dispersed in a matrix of dark relationships. They assert that there is a decoupling between the The most abundant group of minerals in Earth's crust, the structure of silicates are dominated by the silica tetrahedron, SiO44-, with metal ions occurring between tetrahedra). The mesodesmic bonds of the silicon tetrahedron allow extensive polymerization and silicates are classified according to the amount of linking that occurs between the and organic components with respect to measurements involving thermal metamorphism.The finding of Allende-like oxidized lithologies in the reduced Vigarano Work in Progress ... A rock that is a mechanical mixture of different minerals and/or rock fragments (clasts). A breccia may also be distinguished by the origin of its clasts: (monomict breccia: monogenetic or monolithologic, and polymict breccia: polygenetic or polylithologic). The proportions of these fragments within the unbrecciated material, as well as in the Bali-like oxidized member Mokoia, indicates that all four CV3 subgroups derive from a common heterogeneous asteroid. The Bali-like matrix mineralogy was formed by one or more mechanisms; in particular, asteroidal aqueous alteration of material similar to that of the primitive CV3 reduced subgroup at temperatures below 300°C, or re-condensation of vaporized, pre-accretionary, chondritic-rich dust. Grosnaja contains 51 vol% matrix component and exhibits a petrofabric of Roughly 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 flattening (McSween, 1977); this is consistent within the CV group with a A petrographic assessment, using features observed in minerals grains, of the degree to which a meteorite has undergone shock metamorphism. The highest stage observed in 25% of the indicator grains is used to determine the stage. Also called "shock level". of ~S3 (Rubin, 2012). The Bali-like mineralogy of Grosnaja includes the Class of hydroxyl-bearing silicate minerals with a sheet-like structure. They result from aqueous alteration are dominantly serpentine and smectite in meteorites; found in the matrixes of carbonaceous chondrites. Phyllosilicates consist of repeating sequences of sheets of linked tetrahedra (T) and sheets of linked octahedra (O). The T sheet consists of saponite and sodium phlogopite replacing Ca-rich minerals in Roughly 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 and Sub-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. It is unique within its group for containing Name used for a large group of phyllosilicate minerals with the generalized formula X2-3 Y2 O5 (OH)4. Due to their various structures (meteoritics focuses primarily on (Fe, Mg)3Si2O5(OH)4), serpentine can be used to understand the chemistry and progress of aqueous alteration (hydration) of olivine, amphibole, or pyroxene dating back to and chlorite group phyllosilicates, indicative of higher than normal temperatures during alteration. Other Mineral that forms through processes such as weathering, and in the case of meteorites can also include pre-terrestrial alteration. Secondary minerals in meteorites that formed during terrestrial weathering include oxides and hydroxides formed directly from metallic Fe-Ni by oxidation, phosphates formed by the alteration of schreibersite, and sulfates formed by present include magnetite, Pure* iron end-member (Fe2SiO4) of the olivine solid solution series and an important mineral in meteorites. When iron (Fe) is completely substituted by magnesium, it yields the the pure Mg-olivine end-member, forsterite (Mg2SiO4). The various Fe and Mg substitutions between these two end-members are described based on their forsteritic (Fo), andradite, and Ca–Fe-rich pyroxenes. In the Allende-like lithologies which are present in all CV3 subgroups, virtually no phyllosilicate or fayalite is found in the chondrules or CAIs. Instead, nepheline, sodalite, fayalitic olivine, and Ca–Fe-rich pyroxenes are found indicating a higher temperature of alteration than that experienced in the Bali-like lithology on the CV parent asteroid. The high content of magnetite in the Bali-like subgroup was instrumental in The discipline of inferring the Earth’s or any other differentiated parent body's ancient magnetic field and former continental positions through study of remanent magnetization in old rocks from the time of the parent body's formation. In order to study the paleomagnetism of a specimen, the remanent magnetic fields must not studies of type 3.0 Kaba by Gattacceca et al. (2013, 2016). Tentative results suggest a very early (~4.558 b.y. ago) 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. acquisition of a stable magnetic field, consistent with a 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. dynamo within a partially differentiated planetesimal (see the Allende page for further details on the hypothesis for the existence of an internal core dynamo on the CV parent body). The K-type asteroid 599 Luisa has been identified as an asteroidal analog for the Bali-like Work 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 Mokoia. Luisa has a diameter of ~65 km and is located near the 5:2 resonance at ~2.8 The astronomical unit for length is described as the "mean" distance (average of aphelion and perihelion distances) between the Earth and the Sun. Though most references state the value for 1 AU to be approximately 150 million kilometers, the currently accepted precise value for the AU is 149,597,870.66 km. The as well as the ν6 secular resonance, both of which supply fragments into Earth-crossing orbits on relatively short timescales (see diagram below).
Diagram credit: M. M. M. Meier et al., Earth and Planetary Science Letters, vol. 490 (2018)
‘Cosmic history and a candidate parent asteroid for the quasicrystal-bearing meteorite Khatyrka’
(https://doi.org/10.1016/j.epsl.2018.03.025) On the other hand, the ~39 km diameter, C-type asteroid 495 Eulalia was found to have spectral characteristics very similar to Grosnaja, including a ‘featureless’ spectrum, a slight negative slope, and a virtually identical Ratio of the amount of light reflected by an object and the amount of incident light. Albedo is used as a measure of the reflectivity or intrinsic brightness of an object. A white, perfectly reflecting surface has an albedo of 1.0 while a black perfectly absorbing surface would have an (Fieber-Beyer et al., 2008). Moreover, Eulalia is located at the 3:1 Lack of asteroids in regions within the asteroid belt (between Mars and Jupiter) coinciding with orbital periods that are simple fractions of Jupiter’s own orbital period. The absence of asteroids in these gaps is due to resonance with Jupiter’s gravitational influence. (a mean motion resonance located at 2.487 AU) and is predicted to rapidly deliver almost half of its ejected material to Earth crossing orbits; the timing is consistent with the 1.7 m.y. CRE age of Grosnaja. The above specimen of Grosnaja is a 1.5 g partial slice cut from a 20.5 g specimen formerly in the Natural History Museum, Humboldt University, Berlin.