Allendeite
| Allendeite | |
|---|---|
| General | |
| Category | Oxide minerals |
| Formula (repeating unit) | Sc4Zr3O12 |
| IMA symbol | Aed[1] |
| Dana classification | 4.6.8. Simple oxides |
| Crystal system | Trigonal |
| Crystal class | Rhombohedral (3) H–M Symbol: (3) |
| Space group | R3 |
| Unit cell | a = 9.396, c = 8.720 [Å] V = 666.7 Å3 |
| Identification | |
| Crystal habit | Microscopic crystals, inclusions |
| Specific gravity | 4.84 (calculated) |
| Refractive index | 2.14 (calculated) |
| References | [2][3][4] |
Allendeite, Sc4Zr3O12, is an oxide mineral.[2] Allendeite was discovered in a small ultrarefractory inclusion within the Allende meteorite.[2] This inclusion has been named ACM-1.[2] It is one of several scandium rich minerals that have been found in meteorites.[2] Allendeite is trigonal, with a calculated density of 4.84 g/cm3.[2] The new mineral was found along with hexamolybdenum.[2] These minerals, are believed to demonstrate conditions during the early stages of the Solar System, as is the case with many CV3 carbonaceous chondrites such as the Allende meteorite.[2] It is named after the Allende meteorite that fell in 1969 near Pueblito de Allende, Chihuahua, Mexico.[2]
Occurrence[edit]
Allendeite was found as nano-crystals in an ultrarefractory inclusion in the Allende meteorite.[2] The Allende meteorite has shown to be full of new minerals, after nearly forty years it has produced one in ten of the now known minerals in meteorites.[2] This CV3 carbonaceous chondrite was the largest ever recovered on earth and is referred to as the best-studied meteorite in history.[2] The inclusion has only been viewed via electron microscopy.[2] The sample is one centimeter in diameter and has been entrusted to the Smithsonian Institution's National Museum of Natural History with the catalog number USNM7554.[2] One crystal studied is a single 15 x 25 micron size with included perovskite, various osmium-iridium-molybdenum-tungsten alloys, and scandium-stabilized tazheranite.[2] In fact, all allendeite was in contact with perovskite.[2] The grains are anhedral, with no observable crystal forms or twinning.[2]
Significance[edit]
Various scandium rich minerals have been found in meteorites, including; davisite, panguite, kangite, tazheranite, thortveitite, and eringaite.[2] Of these, allendeite is the most Sc rich, with only pretulite containing substantially more scandium.[2]
Appearance[edit]
Color, streak, luster, hardness, tenacity, cleavage, fracture, density, and refractive index could not be observed because the grain size was too small and the section bearing the mineral was optically thick.[2]
See also[edit]
References[edit]
- ^ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
- ^ a b c d e f g h i j k l m n o p q r s t Beckett, John R. and Rossman, George R. = Allendeite (Sc4Zr3O12 and hexamolybdenum (Mo, Ru, Fe), two new minerals from an ultrarefractory inclusion from the Allende meteorite. American Mineralogist, Volume 99, pages 654-666, 2014. doi:10.2138/am.2014.4667
- ^ Allendeite data on Mindat.org
- ^ Allendeite data on Webmin