Carbo

Iron, IID, octahedriteMost Common type of iron meteorite, composed mainly of taenite and kamacite and named for the octahedral (eight-sided) shape of the kamacite crystals. When sliced, polished and etched with an acid such as nitric acid, they display a characteristic Widmanstätten pattern. Spaces between larger kamacite and taenite plates are often

Found 1923
29° 40′ N., 111° 30′ W. A mass of 450 kg was found by cowboys on the Alamo Ranch, which is a station on the Southern Pacific Railroad located 40 miles W of Carbo, Mexico. This 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 was sold to Harvard in 1928, with further distribution of many sections thereafter. Carbo is a low-Ni member of the IID group. The silicateThe 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 cristobaliteHigh temperature polymorph of silicon dioxide (SiO2). Has the same chemical composition as coesite, stishovite, seifertite and tridymite but possesses a different crystal structure. This silica group mineral occurs in terrestrial volcanic rocks, martian and lunar meteorites, chondrites and impact glasses like Libyan Desert Glass. Cristobalite has a very open has been identified in Carbo.

Results of age studies conducted by Kruijer et al. (2012, 2013), utilizing noble gasElement 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. and Hf–W chronometry for those irons that have the lowest CRE ages, indicate coreIn 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. formation began for group IID and IVB irons later than it did for other groups, ~2.0–3.0 m.y. after 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. This is compared to ~1.5–2.0 m.y. after CAIs for groups IIIAB and IVA, and as early as ~1.0–1.5 m.y. after CAIs for groups IIAB and IIIAB.

Noble gas studies by Ammon et al. (2008) have revealed details about the pre-atmospheric measurments of the Carbo meteoroidSmall rocky or metallic object in orbit around the Sun (or another star)., the in situ geometry of Carbo, and its CRE age. Utilizing noble gas concentration data corrected for cosmogenic Ne production contributions from sulfide and phosphate inclusions, a depth profile was developed for Carbo; this profile translates into a pre-atmospheric meteoroid that was generally spherical in shape. Through measurements of the activity of the radionuclideRadioactive isotope - Atomic nuclide that decays radioactively . 36Cl, a diameter of 140 cm was inferred for the Carbo meteoroid. Using this more accurate, corrected data, the team derived a 41K–40K-based CRE age for Carbo of 725 (±100) m.y.

From studies of the 3He distribution in Carbo, it was inferred that at least 5 cm of metalElement 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 has been removed during atmospheric entry and subsequent terrestrial weathering. The 3He distribution was also utilized in a study by Markowski et al. (2006) to determine the initial tungsten isotopic systematics for Carbo and other irons, which revealed that some iron meteorites formed contemporaneously with CAIs within 1 m.y. of the coalescence of the Solar SystemThe Sun and set of objects orbiting around it including planets and their moons and rings, asteroids, comets, and meteoroids..

To learn more of the details of the petrogenesis of the group-IID irons as proposed by Wasson and Huber (2006), click here. The specimen of Carbo pictured above is a 22.5 g deep-etched partial slice. An exquisite etched slice can be seen on display at the Smithsonian Institution, Washington D.C.