Dervillite from Lengenbach: occurrence and crystal structure

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Dervillite from Lengenbach: occurrence and crystal structure

Messaggio #1 da Marco E. Ciriotti il gio 12 dic, 2013 17:00

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
 
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Località: via San Pietro, 55 I-10070 Devesi/Cirié TO - Italy

Re: Dervillite from Lengenbach: occurrence and crystal struc

Messaggio #2 da Marco E. Ciriotti il ven 13 dic, 2013 16:30

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»
Avatar utente
Marco E. Ciriotti
 
Messaggi: 19879
Iscritto il: ven 25 giu, 2004 11:31
Località: via San Pietro, 55 I-10070 Devesi/Cirié TO - Italy


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