(IUCr) Reinvestigation of the crystal structure of lautite, CuAsS

Volume 64
Part 3
Page i22
March 2008

Received 25 January 2008
Accepted 14 February 2008
Online 20 February 2008

Key indicators
Single-crystal X-ray study
T = 298 K
Mean (As-S) = 0.002 Å
R = 0.046
wR = 0.109
Data-to-parameter ratio = 30.2
Details

Reinvestigation of the crystal structure of lautite, CuAsS

Luca Bindi,^a Tiziano Catelani,^b Laura Chelazzi ^b and Paola Bonazzi ^b ^*

^aMuseo di Storia Naturale, Sezione di Mineralogia, Universitá degli Studi di Firenze, Via La Pira 4, I-50121 Firenze, Italy, and ^bDipartimento di Scienze della Terra, Universitá degli Studi di Firenze, Via La Pira 4, I-50121 Firenze, Italy
Correspondence e-mail: pbcry@geo.unifi.it

The crystal structure of the mineral lautite (copper arsenic sulfide), CuAsS, previously described as either centrosymmetric [Pnma; Marumo & Nowacki (1964). Schweiz. Miner. Petro. Mitt. 44, 439-454] or noncentrosymmetric [Pna2₁; Craig & Stephenson (1965). Acta Cryst. 19, 543-547], was reinvestigated by means of single-crystal X-ray diffraction. The centrosymmetric structural model reported previously was confirmed, although with improved precision for the atomic coordinates and interatomic distances. Lautite shows a sphalerite-derivative structure with a linking of Cu[AsS₃], As[CuAs₂S] and S[Cu₃As] tetrahedra. All atoms lie on special positions (Wyckoff position 4c, site symmetry m).

Related literature

For related literature, see: Craig & Stephenson (1965); Marumo & Nowacki (1964); Wyckoff (1963).

Experimental

Crystal data

AsCuS
M_r = 170.54
Orthorhombic, P n m a
a = 11.347 (4) Å
b = 3.7533 (7) Å
c = 5.453 (1) Å
V = 232.24 (10) Å³
Z = 4
Mo K radiation
= 24.00 mm^-1
T = 298 (2) K
0.12 × 0.10 × 0.08 mm

Data collection

Bruker P4 diffractometer
Absorption correction: scan (North et al., 1968) T_min = 0.070, T_max = 0.150
3824 measured reflections
574 independent reflections
483 reflections with I > 2(I)
R_int = 0.077
3 standard reflections every 150 reflections intensity decay: none

Refinement

R[F² > 2(F²)] = 0.046
wR(F²) = 0.108
S = 1.09
574 reflections
19 parameters
_max = 1.28 e Å^-3
_min = -1.07 e Å^-3

Data collection: XSCANS (Bruker, 1997); cell refinement: XSCANS; data reduction: XSCANS; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: Xtaldraw (Downs & Hall-Wallace, 2003); software used to prepare material for publication: SHELXL97.

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: FI2059 ).

Acknowledgements

This work was funded by CNR, Istituto di Geoscienze e Georisorse, Sezione di Firenze.

References

Bruker (1997). XSCANS. Bruker AXS Inc., Madison, Wisconsin, USA.
Craig, D. C. & Stephenson, N. C. (1965). Acta Cryst. 19, 543-547.
Downs, R. T. & Hall-Wallace, M. (2003). Am. Mineral. 88, 247-250.
Marumo, F. & Nowacki, W. (1964). Schweiz. Miner. Petro. Mitt. 44, 439-454.
North, A. C. T., Phillips, D. C. & Mathews, F. S. (1968). Acta Cryst. A24, 351-359.
Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.
Wyckoff, R. W. G. (1963). Crystal Structures, 2nd ed. New York: Interscience Publishers.

inorganic compounds