H5, highly porous
Found September 1998
z+0° 07′ 08′ w+0° 08′ 58′ Five fragments of a Meteorite composed of silicate minerals, but that may have up to 25% Ni-Fe metal by weight. Stony meteorites are extremely heterogeneous as a group, ranging from samples of primordial matter that have remained more or less unchanged for the last 4.56 Ga (chondrites) to highly evolved younger rocks from differentiated were found in the Sahara by a French team. These fragments fit together to constitute a single stone weighing 10.345 kg. The stone was subsequently purchased by Astronomical Research Network, and classification was completed at the Institut für Planetologie in Münster (A. Bischoff). Sahara 98034 was determined to be an H5 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 Click on Term to Read More (Fa18, Fs17) composed 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 Click on Term to Read More and 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 Click on Term to Read More fragments (along with some hollow chondrules) surrounded by an extremely porous groundmass. As is characteristic for members of the H-chondrite group, the fine-grained Fine grained primary and silicate-rich material in chondrites that surrounds chondrules, refractory inclusions (like CAIs), breccia clasts and other constituents. Click on Term to Read More in Sahara 98034 is present in a lower abundance compared to all other Work in Progress Ordinary chondrites (OCs) are the largest meteorite clan, comprising approximately 87% of the global collection and 78% of all falls (Meteoritical Society database 2018)1. Meteorites & the Early Solar System: page 581 section 6.1 OC of type 5 or 6 with an apparent shock stage of S1, Click on Term to Read More groups. This 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 Click on Term to Read More has one of the highest total porosities known among ordinary 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 Click on Term to Read More, determined by X-ray microtomography (µCT) and Helium (He) Second lightest and second most abundant element (after Hydrogen) in the universe. The most abundant isotope is 4He (99.9998%), 3He is very rare. Helium comprises ~8% of the atoms (25% of the mass) of all directly observed matter in the universe. Helium is produced by hydrogen burning inside Click on Term to Read More pycnometry to be ~16% compared to the ~7% typical for most H-group ordinary chondrites (Sasso et al., 2009); Consolmagno et al., 2008).
where bulk density utilizes the full volume enclosed by the outer surface, and grain density utilizes only the volume occupied by solid matter, disregarding cracks and voids (Macke et al., 2011) In their study of 30 ordinary chondrites, it was determined that typical microporosities range from 0% to 27%, with an average of ~6.4%; 95% of the samples had porosities below 20%. In an earlier study by Consolmagno et al. (1998), which utilized a larger data set representing 130 different chondrite porosity values, they demonstrated that the pre-weathering porosity for ordinary chondrites averaged ~10%. The Rare meteorite class named after the Ivuna meteorite that fell in Tanzania in 1938. They are among the most primitive, friable (crumbly), and interesting of all meteorites, having undergone extensive aqueous alteration. They lack chondrules and CAIs as a result of this alteration, but contain up to 20% water, as Click on Term to Read More A large carbonaceous Ivuna-like (CI1) chondrite that disintegrated and fell in fragments near the French town of Orgueil on May 14, 1864. About 20 pieces, totaling ~12 kg in mass, were subsequently recovered from an area of several square km, some head-sized but most were smaller than a fist. Specimens Click on Term to Read More was determined to have the highest porosity of ~35%, and also the lowest measured bulk density (Consolmagno and Britt, 1998). Although they have different bulk compositions, the bulk density of Orgueil compares well to that of certain asteroids, including Phobos, Deimos, and Mathilde. Wilkison et al. (2003) found that the Measure of the degree of aqueous alteration (Types 1 and 2) and thermal metamorphism (Types 3-6) experienced by a chondritic meteorite. Type 3 chondrites are further subdivided into 3.0 through 3.9 subtypes., which corresponds to burial depth, is not correlated with porosity; however, a weak trend for the 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 Click on Term to Read More of porosity as petrologic type increases was found by Macke (2010). Porosity was found to not be correlated with chemical group (e.g., H, L, LL, CM, LUN, AUB, CHA; Strait and Consolmagno, 2004), bulk density, grain density (possibly weakly correlated), brecciation, shock stage (at least not below very strong shock or shock-melt pressure levels), or permeability (Corrigan et al., 1997). Consolmagno et al. (1998) found that terrestrial weathering leads to the filling of the pore spaces on a time scale of hundreds of years, but Coulson et al. (2007) found no relationship between porosity and terrestrial residency time. Furthermore, they found that porosity is not obviously correlated with Physical or chemical process or action that results in the formation of regularly-shaped, -sized, and -patterned solid forms known as crystals. Click on Term to Read More age. Utilizing He pycnometry and microtomography (µCT) techniques, as well as determination of metal particle size distribution, Sasso et al. (2009) investigated the nature of the internal pore spaces in several ordinary chondrites including Sahara 98034. They argue that these meteorites accreted with incomplete compaction and preserve a significant degree of primary accretionary porosity. Although they were less affected by later compaction events, ubiquitous impact-generated microcracks were introduced over time. The lack of any Supersonic flow of high-speed charged particles continuously blowing off a star (mostly e- and p+). When originating from stars other than the Sun, it is sometimes called a "stellar" wind. The solar wind may be viewed as an extension of the corona into interplanetary space. The solar wind emanates radially 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. Click on Term to Read More enrichment suggests that these porous stones were not part of a fine-grained Mixture of unconsolidated rocky fragments, soil, dust and other fine granular particles blanketing the surface of a body lacking an atmosphere. Regolith is the product of "gardening" by repeated meteorite impacts, and thermal processes (such as repeated heating and cooling cycles). Click on Term to Read More. They calculated a total porosity for Sahara 98034 (H5) of 16.1% (±2.0%), while NWA 2380 (LL5) had a higher total porosity of ~18.7% and Miller (H5) had the highest total porosity in the study of ~20%. A study by Wittmann et al. (2010) of the unusual type-5 ordinary chondrite LAP 031047, which has an O-isotopic composition and petrographic features intermediate to H and L chondrites, revealed a very high porosity of ~25–27 vol%. Its porosity is consistent with its weak Metamorphism produced by hypervelocity impact between objects of substantial size moving at cosmic velocity (at least several kilometers per second). Kinetic energy is converted into seismic and heat energy almost instantaneously, yielding pressures and temperatures far in excess those in normal terrestrial metamorphism. On planetary bodies with no atmosphere, smaller Click on Term to Read More (S2–3) given the likelihood that it experienced lithification without compaction, probably reflecting low energy impact events below ~10 GPa. An extensive listing of individual meteorite Mass of an object divided by its volume. Density is a characteristic property of a substance (rock vs. ice, e.g.). Some substances (like gases) are easily compressible and have different densities depending on how much pressure is exerted upon them. The Sun is composed of compressible gases and is much Click on Term to Read More and porosities for all chondrite groups and many An 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 groups is presented by Britt and Consolmagno in MAPS, #8 (2003). Interestingly, they found that porosities of L chondrites (~6%) are significantly different from those of both H and LL chondrites (~10%). Low-density, porous material should be present in regolith breccias of asteroids, created by impact lithification of disordered material, as well as in deep fractures and Fracture along which there has been movement or displacement. Click on Term to Read More zones; the S-type asteroids 433 Eros and 243 Ida, with ~10% microporosity plus ~20% macroporosity, are examples which exhibit both environments. While this may be true, infrared spectra data obtained by the Galileo spacecraft indicate that 243 Ida is most probably an L- or LL-type chondritic asteroid (Granahan, 2013). Results of an Ar–Ar age study by Friedrich et al. (2008) give a best crystallization age for Sahara 98034 of 4.229 (±0.044) b.y., and indicate that the source material was partially reset by an impact-heating event <600 m.y. ago. Although FeNi-metal grains are abundant throughout, some terrestrial weathering effects are evident in Sahara 98034 such as its lower content of metal, 40% less than typical H chondrites; it has a weathering grade of W1 (Sasso et al., 2009). The slice of Sahara 98034 pictured above weighs 56.9 g. The magnified image presented below illustrates the exceptional porosity of this meteorite.
click on photo for a magnified view