Titre du document / Document title

Schreyerite, V₂Ti₃O₉ : New occurrence and crystal structure

Auteur(s) / Author(s)

DÖBELIN Nicola ; REZNITSKY Leonid Z. ; SKLYAROV Evgeny V. ; ARMBRUSTER Thomas ; MEDENBACH Olaf ;

Résumé / Abstract

A new occurrence of schreyerite, V₂Ti₃O₉, has recently been found in metamorphic rocks of the Sludyanka complex at the southern shore of Lake Baikal, Russia. In contrast to previously known schreyerite lamellae, whichare intergrown with rutile, crystals from the Sludyanka complex occur as isolated single crystals associated with titanite, allowing single-crystal X-ray diffraction experiments. The chemical composition was determined with an electron microprobe giving the composition (V_1.785Cr_0.157Fe_0.036)(Ti_2.536V_0.468)O₉. A peculiarity of this schreyerite sample is the partial substitution of V⁴⁺ for Ti⁴⁺. The crystal structure was determined by single-crystal X-ray diffraction and was refined in the monoclinic space group C2/c [a = 17.102(2), b = 5.0253(5), c = 7.0579(8) Å, β = 106.636(10)°] to R₁ = 2.84%. The structure is in agreement with the qualitative model of Grey et al. (1973) determined on the basis of electron diffraction and X-ray powder data for synthetic (Fe,Cr)₂Ti₃O₉. Reinvestigation of schreyerite from the type locality indicates that this sample has cell dimensions and symmetry corresponding to the Sludyanka sample. The structure of schreyerite may be considered as a 1:1 polysome composed of slabs of berdesinskiite, V₂TiO₅, and Ti₂O₄ (a high-pressure phase of TiO₂ with α-PbO₂ structure).

Revue / Journal Title

The American mineralogist   ISSN 0003-004X   CODEN AMMIAY 

Source / Source

2006, vol. 91, n^o1, pp. 196-202 [7 page(s) (article)]

Langue / Language

Anglais

Editeur / Publisher

Mineralogical Society of America, Washington, DC, ETATS-UNIS  (1916) (Revue)

Localisation / Location

INIST-CNRS, Cote INIST : 503, 35400013454443.0240