{"product_id":"muonionalusta-iron-meteorite-slice-33-46g","title":"Muonionalusta Iron Meteorite Slice, IVA Fine Octahedrite, 33.46g, Etched Widmanstatten Pattern","description":"\u003ch2\u003eAn etched slice of an asteroid core\u003c\/h2\u003e\n\u003cp\u003eThis 33.46g slice of Muonionalusta has been etched on both sides to bring out the Widmanstatten pattern, the interlocking kamacite and taenite bands that grew as the nickel-iron core of a differentiated asteroid cooled. Muonionalusta is classified in the Meteoritical Bulletin as Iron, IVA, and was first recorded in the Bulletin as an iron of fine octahedrite structure.\u003c\/p\u003e\n\u003cp\u003eOne face is polished and etched. The reverse is etched without polishing, so the pattern there shows on an unpolished surface and reads differently from the polished side, and part of the reverse retains exterior surface from the original mass. The slice has been fully stabilized and finished with a light protective coating. It carries no epoxy. At this size it suits a first iron meteorite, a cabinet drawer, or a desk where the pattern can be seen up close.\u003c\/p\u003e\n\n\u003ch2\u003eStructure and features\u003c\/h2\u003e\n\u003cp\u003eThe Widmanstatten pattern is a three dimensional intergrowth of two nickel-iron alloys. Kamacite, which is low in nickel, formed as plates along the octahedral planes of the parent taenite crystal as the metal cooled. Etching with dilute acid attacks the two phases at different rates, so the bands stand out against each other on a polished face.\u003c\/p\u003e\n\u003cp\u003eIn a fine octahedrite the kamacite bands are narrow, which gives a tight, closely spaced pattern rather than the broad bands of coarser irons. The angle at which a slice crosses the original crystal determines how the bands appear on any given face, so the geometry varies from slice to slice even within the same mass.\u003c\/p\u003e\n\u003cp\u003eThe protective coating is applied to slow oxidation of the etched metal. Iron meteorites react with moisture, and stabilization and a sealing coat are the standard ways to protect an etched surface over time.\u003c\/p\u003e\n\n\u003ch2\u003eDiscovery and provenance\u003c\/h2\u003e\n\u003cp\u003eMuonionalusta comes from Norrbotten in northern Sweden, where the first mass was found in 1906. The Meteoritical Bulletin records the find year as 1906, the country as Sweden, and a mass of 230 kg. That figure reflects the early finds; systematic searching in the decades since has recovered a great deal more material, so it should not be read as the total that exists today. The Bulletin itself cautions that its recorded masses are not authoritative.\u003c\/p\u003e\n\u003cp\u003eThis specimen was acquired by Treasure Coast Meteorite Co.\u003c\/p\u003e\n\n\u003ch2\u003eScientific context\u003c\/h2\u003e\n\u003cp\u003eIVA irons are thought to come from the metallic core of a parent body that melted and separated into metal and rock early in the history of the solar system. Slow cooling of that core over a very long time allowed the kamacite and taenite to separate into the coarse crystal intergrowth that etching reveals. Later collisions broke the parent body apart and exposed core material that eventually reached Earth.\u003c\/p\u003e\n\u003cp\u003eAs of October 2026, the Meteoritical Bulletin lists this as 1 of 88 approved meteorites classified as Iron, IVA. That is a count of database entries; some entries may later be shown to be paired.\u003c\/p\u003e\n\n\u003ch2\u003eThe story\u003c\/h2\u003e\n\u003cp\u003eThe first piece of Muonionalusta was found in 1906 in the forests of Swedish Lapland, north of the Arctic Circle. According to the locality record, it was found by a 10 year old boy tending cattle in the forest southwest of the village of Kitkiojarvi. The meteorite takes its name from Muonionalusta, a place on the Muonio River along the border between Sweden and Finland.\u003c\/p\u003e\n\u003cp\u003eThe Bulletin records two of the early recoveries in its own pages. Meteoritical Bulletin 20 reports a second mass of about 15 kg, found on 15 August 1946 during earthwork at a building site roughly 8 km east southeast of the 1906 find. Meteoritical Bulletin 28 reports a third, a single 6.20 kg mass found on 7 June 1963 by Carl Henriksson in excavated material used to build a causeway, about 3.5 km east northeast of the village. That mass went to the Swedish Museum of Natural History in Stockholm.\u003c\/p\u003e\n\u003cp\u003eFinds stayed slow for most of the twentieth century. Searching with metal detectors since the late 1980s has recovered many more masses from the glacial till of the region, some from several meters down. They sit in till because they have been on Earth a very long time: Holtstam and colleagues cite a terrestrial age of more than 800,000 years from cosmogenic beryllium-10 and chlorine-36, long enough for the masses to have lived through several major glaciations.\u003c\/p\u003e\n\u003cp\u003eSources: Meteoritical Bulletin 20 (1961) and 28 (1963), as reproduced in the \u003ca href=\"https:\/\/www.lpi.usra.edu\/meteor\/metbull.cfm?code=16873\" target=\"_blank\" rel=\"noopener\"\u003eMeteoritical Bulletin Database entry\u003c\/a\u003e; Holtstam et al. (2003), cited below; \u003ca href=\"https:\/\/www.mindat.org\/loc-14560.html\" target=\"_blank\" rel=\"noopener\"\u003eMindat locality record for Muonionalusta\u003c\/a\u003e; \u003ca href=\"https:\/\/www.researchgate.net\/publication\/327363885_The_Muonionalusta_iron_meteorites_from_Lapland_Sweden_New_finds_and_findings\" target=\"_blank\" rel=\"noopener\"\u003eThe Muonionalusta iron meteorites from Lapland, Sweden: New finds and findings\u003c\/a\u003e.\u003c\/p\u003e\n\n\u003ch2\u003eWhat the research reports\u003c\/h2\u003e\n\u003cp\u003eThe Meteoritical Bulletin classifies Muonionalusta as Iron, IVA. Its classification history begins as Iron-fine octahedrite in Meteoritical Bulletin 20 (1961), with the IVA group assigned in the Natural History Museum Catalogue of Meteorites (2000) and in MetBase (2006). The database records iron meteorites by chemical group only, which is why the current recommended classification does not include the structural term. Fine octahedrite is used on this listing because the Bulletin's own 1961 record uses it, and because the entry links Buchwald's Handbook of Iron Meteorites (1975, volume 3, page 865) for the structural description. The studies below come from the authors' own samples and methods, and are given here as the studies state them.\u003c\/p\u003e\n\n\u003ch3\u003eHoltstam et al. (2003): stishovite in an iron meteorite\u003c\/h3\u003e\n\u003cp\u003eD. Holtstam, C. Broman, J. Soderhielm and A. Zetterqvist published \u003ca href=\"https:\/\/doi.org\/10.1111\/j.1945-5100.2003.tb00002.x\" target=\"_blank\" rel=\"noopener\"\u003eFirst discovery of stishovite in an iron meteorite\u003c\/a\u003e (Meteoritics and Planetary Science, volume 38, pages 1579 to 1583, 2003). Stishovite is a very high pressure form of silica, and Muonionalusta was the first iron meteorite in which it had been found.\u003c\/p\u003e\n\n\u003ch3\u003eBlichert-Toft et al. (2010): an early age for the IVA core\u003c\/h3\u003e\n\u003cp\u003eJ. Blichert-Toft, F. Moynier, C.-T. A. Lee, P. Telouk and F. Albarede published \u003ca href=\"https:\/\/www.sciencedirect.com\/science\/article\/abs\/pii\/S0012821X10003651\" target=\"_blank\" rel=\"noopener\"\u003eThe early formation of the IVA iron meteorite parent body\u003c\/a\u003e (Earth and Planetary Science Letters, volume 296, pages 469 to 480, 2010). Lead isotopes in the troilite inclusions of Muonionalusta gave an age of 4,565.3 plus or minus 0.1 million years, placing the solidification of the IVA core within a few million years of the first solids in the solar system. The authors describe the meteorite as \"heavily shocked,\" possibly during the breakup of the parent body about 400 million years ago.\u003c\/p\u003e\n\n\u003ch3\u003eBrennecka et al. (2018): a caveat on that age\u003c\/h3\u003e\n\u003cp\u003eA later study led by G. A. Brennecka, \u003ca href=\"https:\/\/www.sciencedirect.com\/science\/article\/abs\/pii\/S0012821X18301328\" target=\"_blank\" rel=\"noopener\"\u003eUranium isotope ratios of Muonionalusta troilite and complications for the absolute age of the IVA iron meteorite core\u003c\/a\u003e (Earth and Planetary Science Letters, 2018), measured the uranium isotope ratio in Muonionalusta troilite directly. The 2010 age relied on an assumed uranium isotope ratio, and the new measurements complicate the absolute age, so the 4,565.3 million year figure is best read with that caveat.\u003c\/p\u003e\n\n\u003ch2\u003eFrequently asked questions\u003c\/h2\u003e\n\u003cp\u003e\u003cstrong\u003eWhat is the official classification?\u003c\/strong\u003e\u003cbr\u003eThe Meteoritical Bulletin classifies Muonionalusta as Iron, IVA. It was first recorded in Meteoritical Bulletin 20 (1961) as an iron of fine octahedrite structure. The full entry is linked at the end of this listing.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eIs this specimen coated?\u003c\/strong\u003e\u003cbr\u003eYes. It has a light protective coating to help preserve the etched surface. There is no epoxy on this specimen.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eAre both sides finished the same way?\u003c\/strong\u003e\u003cbr\u003eNo. Both sides are etched, but only one side is polished. The polished side shows the pattern with the sharpest contrast; the unpolished side shows it on a rougher surface and includes some exterior surface from the original mass.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eHas it been stabilized?\u003c\/strong\u003e\u003cbr\u003eYes. The slice has been fully stabilized before finishing. Stabilization reduces the risk of rust developing from within the metal, which is the main long term concern with iron meteorites.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eHow should I care for it?\u003c\/strong\u003e\u003cbr\u003eStore it in a dry place and handle it by the edges. Skin oils and humidity are the main causes of spotting on etched iron. Avoid cleaning it with water or household cleaners.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWhat makes the Widmanstatten pattern visible?\u003c\/strong\u003e\u003cbr\u003eEtching. The pattern is present throughout the metal, but on a cut and polished face it is not visible until a dilute acid etch attacks the kamacite and taenite at different rates and creates contrast between the bands.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eIs a display stand included?\u003c\/strong\u003e\u003cbr\u003eNo. Only the specimen is included unless otherwise stated.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWho is the seller?\u003c\/strong\u003e\u003cbr\u003eTreasure Coast Meteorite Co. is an IMCA member, #3323, based in Hobe Sound, Florida.\u003c\/p\u003e\n\n\u003ch2\u003eCollector significance\u003c\/h2\u003e\n\u003cp\u003eMuonionalusta combines a long and well documented find history, a classification that runs back to the Bulletin's records of 1961, and a published research record that includes the first stishovite found in an iron meteorite and one of the oldest ages measured for an iron meteorite core. A 33.46g etched slice puts all of that in a piece small enough to hold in one hand.\u003c\/p\u003e\n\u003cp\u003eSee more specimens of this meteorite in the \u003ca href=\"\/de\/collections\/muonionalusta\"\u003eMuonionalusta collection\u003c\/a\u003e and other irons in the \u003ca href=\"\/de\/collections\/iron-meteorites\"\u003eIron Meteorites collection\u003c\/a\u003e. For background on how the pattern forms, see \u003ca href=\"\/de\/pages\/widmanstatten-pattern-explained\"\u003ethe Widmanstatten pattern explained\u003c\/a\u003e.\u003c\/p\u003e\n\u003cp\u003eMeteoritical Bulletin entry: \u003ca href=\"https:\/\/www.lpi.usra.edu\/meteor\/metbull.cfm?code=16873\" target=\"_blank\" rel=\"noopener\"\u003eMuonionalusta\u003c\/a\u003e. Classification: Iron, IVA. Find, Sweden, 1906. Treasure Coast Meteorite Co., IMCA #3323.\u003c\/p\u003e","brand":"Treasure Coast Meteorite Co.","offers":[{"title":"Default Title","offer_id":47008194494511,"sku":"MUONIONALUSTA-33.46G-SLICE-ETCHED","price":160.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0726\/9724\/9839\/files\/muonionalusta-iron-iva-33.46g-polished-etched-face.jpg?v=1792270166","url":"https:\/\/www.tcmeteorites.com\/de\/products\/muonionalusta-iron-meteorite-slice-33-46g","provider":"Treasure Coast Meteorite Co.","version":"1.0","type":"link"}