Kumdykolite, a high-temperature feldspar from an enstatite chondrite

Németh, Péter and Stephen, Lehner W. and Petaev, Michail I. and Buseck, Peter R. (2013) Kumdykolite, a high-temperature feldspar from an enstatite chondrite. AMERICAN MINERALOGIST, 98 (5-6). pp. 1070-1073. ISSN 0003-004X

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We report the first occurrence of kumdykolite in a meteorite (Sahara 97072, EH3). This orthorhombic form of albite occurs in the core of a concentrically zoned metal-sulfide nodule. In contrast to the terrestrial kumdykolite, the meteoritic sample has a domain structure that is consistent with either orthorhombic (Pmnn) or monoclinic (P21) space groups. The two symmetries are indicated by the presence or lack, respectively, of h + k = 2n + 1 reflections in [001] selected-area electron diffraction patterns, effects that likely result from different Si-Al ordering. Pmnn kumdykolite has only one tetrahedral site for Si and Al, whereas P21 kumdykolite would have three tetrahedral sites for Si and one for Al. We propose that kumdykolite formed above 1300 K and cooled rapidly enough to preserve its unique structure. Apparently, the cooling rate varied on the scale of nanometers allowing the local development of Si-Al ordering.

Item Type: Article
Uncontrolled Keywords: symmetry; Feldspar; DIFFRACTION; cooling; albite; Si-Al ordering; Kumdykolite; ENSTATITE CHONDRITE; Domain structure; Albite polymorph
Subjects: G Geography. Anthropology. Recreation / földrajz, antropológia, kikapcsolódás > GE Environmental Sciences / környezettudomány
Q Science / természettudomány > QD Chemistry / kémia
Q Science / természettudomány > QD Chemistry / kémia > QD06 Mineralogy / ásványtan
Q Science / természettudomány > QE Geology / földtudományok
Depositing User: MTMT SWORD
Date Deposited: 28 Jun 2013 10:37
Last Modified: 28 Jun 2013 11:03

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