Dervillite from Lengenbach: occurrence and crystal structure

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Marco E. Ciriotti
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Dervillite from Lengenbach: occurrence and crystal structure

Messaggioda Marco E. Ciriotti » gio 12 dic, 2013 16:00

Referenza:
▪ Bindi, L., Nestola, F., de Battisti, L., Guastoni, A. (2013): Dervillite, Ag2AsS2, from Lengenbach quarry, Binn valley, Switzerland: occurrence and crystal structure. Mineralogical Magazine, 77, 3105–3112.

Abstract:
Dervillite, Ag2AsS2, has been found in a sample from the Lengenbach quarry in the Binn Valley, Valais, Switzerland. It occurs as very rare crystals up to 200 mm across on jordanite. Dervillite is opaque with a metallic lustre and shows a dark brown streak. The structure is monoclinic, space group Pc, with a = 9.6155(7), b = 12.9331(8), c = 6.8616(5) A˚, beta = 99.352(8)º, V = 842.0(1) A˚ 3 and Z = 8. In the crystal structure [R1 = 0.060 for 2370 reflections with I > 2s(I)], silver adopts various coordinations extending from quasi linear to quasi tetrahedral whereas arsenic forms very peculiar crystal-chemical environments, such as As(S2As) and As(S2AsAg). Such metalloid–metalloid or metal–metalloid bonds account for the apparent charge imbalance observed in the chemical formula.
Marco E. Ciriotti

«Things are interesting only in so far as they relate themselves to other things»

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Marco E. Ciriotti
Messaggi: 20260
Iscritto il: ven 25 giu, 2004 11:31
Località: via San Pietro, 55 I-10070 Devesi/Cirié TO - Italy
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Re: Dervillite from Lengenbach: occurrence and crystal struc

Messaggioda Marco E. Ciriotti » ven 13 dic, 2013 15:30

Un bell'esempio di soluzione di strutture irrisolte che comporta automaticamente la variazione di status da Q a Rd.
Marco E. Ciriotti



«Things are interesting only in so far as they relate themselves to other things»


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