TY - JOUR

T1 - New data on the crystal structures of colusites and arsenosulvanites

AU - Frank-Kamenetskaya, O. V.

AU - Rozhdestvenskaya, I. V.

AU - Yanulova, L. A.

PY - 2002/1/1

Y1 - 2002/1/1

N2 - The crystal structures of three minerals (arsenosulvanite, V,As-germanite, and colusite) of the general crystal chemical formula CuM2-xVM2Cu26-y(As, Ge, Sn, Sb, V)6S32, where CuM, VM are cations at interstitial positions, 0.2 ≤ x ≤ 2.0, 2.7 ≥ y ≥ 0, (space group P43n, a = 10.527; 10.600; 10.653 Å; R = 0.066; 0.046; 0.033) have been determined using single-crystal X-ray diffraction data. The minerals are the two structural modifications of the compound with the ideal formula V2Cu24As6S32; they differ from each other in the occupancy of the interstitial position 2a. In colusite, this position is occupied by the V5+ cations; in arsenosulvanite and V,As-germanite, by Cu+. A characteristic feature of the structures is the presence of octahedral [T′S4]Cu6 (T′ = V, Cu) complexes not directly interacting with each other and lying inside the Laves polyhedra. In the structures of arsenosulvanite and V,As-germanite, a sulvanite framework consisting of interpenetrating Laves polyhedra T ′T3S4 (T′ = V, Cu; T = Cu, As, Ge) has been found. The sulvanite framework is statistically distributed over the sphalerite matrix. The variable composition of the minerals is due to heterovalent isomorphism in the sphalerite position 6c. Charge disbalance arising from substitution of the pentavalent arsenic cations by cations of lower valence is compensated by the appearance of additional Cu+ cations. The nonstoichiometry of the compositions is explained by the presence of vacancies in the interstitial and sphalerite positions.

AB - The crystal structures of three minerals (arsenosulvanite, V,As-germanite, and colusite) of the general crystal chemical formula CuM2-xVM2Cu26-y(As, Ge, Sn, Sb, V)6S32, where CuM, VM are cations at interstitial positions, 0.2 ≤ x ≤ 2.0, 2.7 ≥ y ≥ 0, (space group P43n, a = 10.527; 10.600; 10.653 Å; R = 0.066; 0.046; 0.033) have been determined using single-crystal X-ray diffraction data. The minerals are the two structural modifications of the compound with the ideal formula V2Cu24As6S32; they differ from each other in the occupancy of the interstitial position 2a. In colusite, this position is occupied by the V5+ cations; in arsenosulvanite and V,As-germanite, by Cu+. A characteristic feature of the structures is the presence of octahedral [T′S4]Cu6 (T′ = V, Cu) complexes not directly interacting with each other and lying inside the Laves polyhedra. In the structures of arsenosulvanite and V,As-germanite, a sulvanite framework consisting of interpenetrating Laves polyhedra T ′T3S4 (T′ = V, Cu; T = Cu, As, Ge) has been found. The sulvanite framework is statistically distributed over the sphalerite matrix. The variable composition of the minerals is due to heterovalent isomorphism in the sphalerite position 6c. Charge disbalance arising from substitution of the pentavalent arsenic cations by cations of lower valence is compensated by the appearance of additional Cu+ cations. The nonstoichiometry of the compositions is explained by the presence of vacancies in the interstitial and sphalerite positions.

UR - http://www.scopus.com/inward/record.url?scp=0036294173&partnerID=8YFLogxK

U2 - 10.1023/A:1016077917390

DO - 10.1023/A:1016077917390

M3 - Article

AN - SCOPUS:0036294173

VL - 43

SP - 89

EP - 100

JO - Journal of Structural Chemistry

JF - Journal of Structural Chemistry

SN - 0022-4766

IS - 1

ER -