krotite - Astronomy News

Blobrana

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Posts: 131433

Date: Jun 23 02:37 2011

Calcium-aluminium-rich inclusions	Permalink

Calcium-aluminium-rich inclusions Calcium-aluminium-rich inclusions (CAIs) are the oldest solids to form in the Solar System. They occur in every type of chondrite, but are particularly abundant and well studied in the Allende carbonaceous chondrite. Justin Simon (University of California, Berkeley, but now at the Johnson Space Centre) and colleagues at Berkeley, Lawrence Livermore National Laboratory, and the University of Chicago analysed the oxygen isotopic composition of a CAI (designated A37) and its rim, using a nanoSIMS to obtain micrometer spatial resolution. They found that the abundances of oxygen isotopes varied: It is high in oxygen-16 in the center of the inclusion, low near the rim, and then high again in the outer rim. Cosmochemists have concluded that CAIs formed close to the Sun (inside the orbit of Mercury, though Mercury was not present at the time), where oxygen-16 was highest. The decrease near the rim of the inclusion A37 indicates that the CAI must have travelled to a part of the dusty early Solar System where oxygen-16 was relatively less abundant, which is further from the Sun, perhaps around the asteroid belt. The increase in oxygen-16 in the rim indicates that the inclusion again moved to a region rich in oxygen-16, probably back to the region near the Sun, and then travelled back to where asteroids formed so it could be incorporated into the parent body of the Allende meteorite. This wandering is consistent with other observations that suggest transport of materials from the inner to the outer solar nebula, but this is the first documentation of small objects migrating back in towards the Sun. Read more (880kb, PDF) __________________

Blobrana

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Posts: 131433

Date: May 16 20:58 2011

RE: krotite	Permalink

Kingsborough Community College Professor and Team of Scientists Publish Paper Announcing Discovery of New Mineral Dr. Regina Peruggi, president of Kingsborough Community College (KCC), today announced that Dr. Harold C. Connolly, Jr., a KCC Department of Physical Sciences professor, and Stuart A. Sweeney Smith, who worked with Professor Connolly at the American Museum of Natural History (AMNH) as a City University of New York undergraduate intern, are among a team of scientists that has discovered a new mineral, named krotite. The discovery was revealed in a paper published in the May-June issue of the American Mineralogist. Krotite was found in a 4.5 billion-year-old meteorite and is one of the earliest minerals formed in our solar system. It is the main component of an unusual inclusion embedded in a meteorite (NWA1934) found in northwest Africa. Krotite is named for Alexander N. Krot, a cosmochemist at the University of Hawaii, in recognition of his significant contributions to the understanding of early solar system processes. Read more __________________

Blobrana

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Posts: 131433

Date: May 9 09:20 2011

NWA 1934 meteorite	Permalink

Paper announces discovery of 1 of earliest minerals formed in solar system In the May-June issue of the journal American Mineralogist, a team of scientists announced the discovery of the new mineral krotite, one of the earliest minerals formed in our solar system. It is the main component of an unusual inclusion embedded in a meteorite (NWA 1934), found in northwest Africa. These objects, known as refractory inclusions, are thought to be the first planetary materials formed in our solar system, dating back to before the formation of the Earth and the other planets. This particular grain is known affectionately as "Cracked Egg" for its distinctive appearance. Dr. Harold C. Connolly, Jr. and student Stuart A. Sweeney Smith at the City University of New York (CUNY) and the American Museum of Natural History (AMNH) first recognised the grain to be of a very special type, known as a calcium-aluminium-rich refractory inclusion. ("Refractory" refers to the fact that these grains contain minerals that are stable at very high temperature, which attests to their likely formation as very primitive, high-temperature condensates from the solar nebula.) Read more __________________

Blobrana

L

Posts: 131433

Date: May 7 15:18 2011

krotite

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New mineral, krotite, named after UH Manoa researcher

The first natural occurrence of a low-pressure CaAl2O4 mineral has been found in a refractory inclusion in a carbonaceous chondrite meteorite. While synthetic low-pressure and high-pressure CaAl2O4 phases are well known in the field of materials science, only the high-pressure polymorph had been identified previously in nature (in another chondrite). Quantitative elemental microanalysis of the new mineral using the electron microprobe resulted in an empirical formula (based on four oxygens) of Ca1.02Al1.99O4. It is now officially approved by the Commission on New Minerals, Nomenclature, and Classification of the International Mineralogical Association as 'krotite'.
Krotite is the dominant mineral in the central and mantle areas of an unusual CAI in the NWA 1934 carbonaceous chondrite.
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