Naslov
Order disorder in hyalophane feldspar: NMR study

Autori
Bermanec, Vladimir ; Sherriff, Barbara L.

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
18th General Meeting of the International Mineralogical Association - Programme with abstracts / - Edinburgh : International Mineralogical Association, 2002

Skup
18th General Meeting of the International Mineralogical Association

Mjesto i datum
Edinburgh, Ujedinjeno Kraljevstvo, 01.09.2002. - 06.09.2002

Vrsta sudjelovanja
Poster

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
hyalophane; NMR spectra

Sažetak
Hyalophane is a Ba rich feldspar which is along the join of orthoclase, celsian and albite. There is no yet published data about NMR of hyalophane or celsian and there is no real data about order disorder within this feldspar. The spectra are interpreted by comparing with papers on alkali feldspar and anorthite (Phillips et al. 1988, 1992 ; Sherriff and Hartman 1985). The interpretation of NMR peaks has caused some difficulty. It was possible to fit four peaks but there may be more than was possible to resolve. Phillips et al. (1992) were able to resolve eight peaks corresponding to the eight crystallographical environments for Si in anorthite. According to de Pieri and Quareni (1977) there are two T sites in both low and high hyalophane. However the spectra are easier to interpret if there are four T sites as in low temperature albite and orthoclase. In accordance with the allocation of peaks for feldspars I would assign these peaks to T1o (-88.4 ppm), T2o (-91.5 ppm), T1m (-95.6 ppm) and T2m (-101.0 ppm). Then the four sites would have a Si occupation of 0.5, 0.6 1.0, and 0.5 respectively. This means that the Al is spread over 3 sites T1o T2o and T2m. Although there are some informations about exholutions within hyalophane (Viswanathan and Kielhorn, 1983 ; Nakano, 1979) in this case there is no evidence for that on the basis of electron microscopy, polarizing microscopy and X-ray diffraction investigations

Izvorni jezik
Engleski

Znanstvena područja
Geologija

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