Original paper

Crystal structure and microtwinning of K-rich nenadkevichite

Rastsvetaeva, Ramiza K.; Tamazyan, Rafael A.; Pushcharovsky, Dmitriy Yu.; Nadezhina, Tamara N.

European Journal of Mineralogy Volume 6 Number 4 (1994), p. 503 - 510

10 references

published: Jul 27, 1994
manuscript accepted: Oct 2, 1993
manuscript received: Mar 29, 1994

DOI: 10.1127/ejm/6/4/0503

BibTeX file

ArtNo. ESP147050604011, Price: 29.00 €

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Abstract

Abstract Potassium-rich nenadkevichite, Na0.6K1.5{(Nb0.6Ti0.4)(Nb0.5Ti0.5)[Si4O12](O,OH)2}∙1.6H2O, M = 582.9, monoclinic, space group Cm, a = 14.692(4), b = 14.164(4), c = 7.859(3) Å, β = 117.87(2)°, V = 1445.7(1) Å3, Z = 4, ρc = 2.67 g/cm3, λ(MoKα) = 0.71073 Å, μ = 22.16 cm-1, dimensions (mm) 0.2 x 0.3 x 0.4, F(000) = 1120.32, room temperature, R = 0.055 for 1443 reflections with IFI > 3σ(F), twinned crystal, the twinning index n = 2. The crystal structure, like the other members of the labuntsovite nenadkevichite group, contains columns formed by (Nb,Ti)-octahedra with shared trans-vertices. The octahedral columns are linked by tetrahedral four-membered rings [Si4O12]∙ The statistically distributed K, Na-ions and water molecules are located in the channels of the mixed framework.

Keywords

nenadkevichitecrystal structuresilicate mineral