LL3.7 Fell February 1857 9° 14′ N., 78° 21′ E. On February 28, 1857, at 12:00 noon, sonic booms were heard followed by the 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 of two stones weighing 134 pounds and 37 pounds. Parnallee is said to be 16 miles south of Madura, India, but no village with this name can be traced in the area. The place of fall is probably Perunali, Ramnad district, 52 miles SSE of Madura.
This is a very primitive 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 full of slightly flattened 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 (ave. 10% deformation) ranging in size from 0.2 mm to 2.5 mm, but some as large as 4 mm have been identified. They include radial pyroxeneA class of silicate (SiO3) minerals that form a solid solution between iron and magnesium and can contain up to 50% calcium. Pyroxenes are important rock forming minerals and critical to understanding igneous processes. For more detailed information, please read the Pyroxene Group article found in the Meteoritics & Classification category. Click on Term to Read More, barred olivineGroup 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 Click on Term to Read More, and porphyritic types. Shock effects include fractured olivine and extensive undulatory extinctionIn astronomy, the dimming of starlight as it passes through the interstellar medium. Dust scatters some of the light, causing the total intensity of the light to diminish. It is important to take this effect into account when measuring the apparent brightness of stars. The dark bands running across portions Click on Term to Read More, likely the result of the impact shock that also produced the chondruleRoughly 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 foliation. In a study of two LL 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, NWA 1701 and LAR 06298, Weirich et al. (2009) determined an Ar–Ar age of ~1 b.y., possibly reflecting the last major impact on the LL chondriteOrdinary chondrites ("low Fe" / "low metal") with only 1 to 3% free metal. Their olivine is more Fe-rich than in the other ordinary chondrites (Fa27-32), implying that the LL types must have formed under more oxidizing conditions than their H or L cousins. Orthopyroxene compositions are also Fe-the rich Click on Term to Read Moreparent bodyThe 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. Click on Term to Read More. A shock stageA 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". Click on Term to Read More of S3 was determined for Parnallee.
Parnallee was previously classified as an LL3.6 ordinary chondriteWork 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, consistent with results from the technique of induced thermoluminescence. However, utilizing Raman spectroscopyTechnique of splitting electromagnetic radiation (light) into its constituent wavelengths (a spectrum), in much the same way as a prism splits light into a rainbow of colors. Spectra are not smooth but punctuated by 'lines' of absorption or emission caused by interaction with matter. The energy levels of electrons in along with other independent petrologic tracers (i.e., 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. Click on Term to Read More content, presolar grain abundance, and zoning of olivine phenocrysts), Bonal et al. (2006) concluded that the actual petrologic typeMeasure 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. of Parnallee should lie between 3.7 and 3.8, and they suggested a classification of LL3.7 as most appropriate.
Most of the 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 Click on Term to Read More and sulfide in 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 Click on Term to Read More occurs between chondrules, but some resides in both the interior and along the rims of chondrules. Much of the glassy mesostasisLast material to crystallize/solidify from a melt. Mesostasis can be found in both chondrules, in the matrix around chondrules, and in achondrites as interstitial fine-grained material such as plagioclase, and/or as glass between crystalline minerals. Click on Term to Read More within the chondrules has been devitrified to very fine-grained aggregates, but some chondrules preserve a transparent, isotropicSame in all directions. Click on Term to Read More, brown glass. Light brown limonitic staining around metal particles is widespread but not pervasive, and does not mask the primary textures of the chondrules. Investigators have identified an achondritic clastA mineral or rock fragment embedded in another rock. Click on Term to Read More (a microgabbro), as well as a chondritic clast that is isotopically related to carbonaceous chondrites (Sokol et al., 2007 and references therein). The presence of nepheline replacing anorthiteRare compositional variety of plagioclase and the calcium end-member of the plagioclase feldspar mineral series with the formula CaAl2Si2O8. Anorthite is found in mafic igneous rocks such as anorthosite. Anorthite is abundant on the Moon and in lunar meteorites. However, anorthite is very rare on Earth since it weathers rapidly Click on Term to Read More in some porphyritic chondrules in Parnallee is an indication of early alkali metasomatism on the LL parent body (Lewis and Jones, 2014). These metasomatic fluids might have been introduced through the infall of carbonaceous chondriteCarbonaceous chondrites represent the most primitive rock samples of our solar system. This rare (less than 5% of all meteorite falls) class of meteorites are a time capsule from the earliest days in the formation of our solar system. They are divided into the following compositional groups that, other than Click on Term to Read More material.
Trapped primitive noble gasesElement 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 in various components of Parnallee comprise primordial Q-gas, Ar-rich gas, and a subsolar component (Matsuda et al., 2010). Based on these noble gases, a CRE age of 6.8–10 m.y. was calculated for Parnallee. The specimen of Parnallee shown above is a 2.4 g partial slice, while the photo below shows a large cut slab, courtesy of the Elbert A. King Collection, which shows the rich concentration of chondrules in this meteorite.
