research papers
Petzite, Ag3AuTe2, crystallizes in the space group I4132, which is a Sohncke type of space group where chiral crystal structures can occur. The structure refinement of petzite reported long ago [Frueh (1959). Am. Mineral. 44, 693–701] did not provide any information about the absolute structure. A new single-crystal X-ray diffraction refinement has now been performed on a sample from Lake View Mine, Golden Mile, Kalgoorlie, Australia, which has resulted in a reliable absolute structure [a Flack parameter of 0.05 (3)], although this corresponds to the opposite enantiomorph reported previously. The minimum Te–Te distance is 3.767 (3) Å, slightly shorter than the van der Waals bonding distance, which suggests a weak interaction between the two chalcogens. XANES spectra near the Au and Te LIII edges suggest that the chemical-bonding character of Au in petzite is more metallic than in other gold minerals.
Keywords: petzite; gold minerals; single-crystal structure analysis; Au L-edge XANES; Debye temperature.
Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S2052520619002166/je5009sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S2052520619002166/je5009Isup2.hkl |
CCDC reference: 1896511
Computing details top
Program(s) used to solve structure: Jana2006; program(s) used to refine structure: Jana2006; molecular graphics: VESTA; software used to prepare material for publication: LibreOffice Writer.
(I) top
Crystal data top
Ag3AuTe2 | Dx = 9.118 Mg m−3 |
Mr = 775.8 | Mo Kα radiation, λ = 0.71069 Å |
Cubic, I4132 | Cell parameters from 2866 reflections |
Hall symbol: I 4bd 2c 3 | θ = 4.8–27.4° |
a = 10.417 (8) Å | µ = 46.08 mm−1 |
V = 1130.3 (15) Å3 | T = 297 K |
Z = 8 | Cube, grey |
F(000) = 2592 | 0.07 × 0.05 × 0.03 mm |
Data collection top
Rigaku R-AXIS RAPID diffractometer | 225 independent reflections |
Radiation source: X-ray tube | 176 reflections with I > 3σ(I) |
Graphite monochromator | Rint = 0.097 |
Detector resolution: 10.000 pixels mm-1 | θmax = 27.4°, θmin = 4.8° |
ω scans | h = −13→11 |
Absorption correction: integration Busing, W.R. and Levy, H.A. 1957. High-Speed Computation of the Absorption Correction for Single Crystal Diffraction Measurements. Acta Cryst. 10, 180-182. | k = −13→13 |
Tmin = 0.085, Tmax = 0.251 | l = −13→12 |
2866 measured reflections |
Refinement top
Refinement on F2 | 0 constraints |
R[F2 > 2σ(F2)] = 0.030 | Weighting scheme based on measured s.u.'s w = 1/(σ2(I) + 0.0004I2) |
wR(F2) = 0.052 | (Δ/σ)max = 0.005 |
S = 1.04 | Δρmax = 1.74 e Å−3 |
225 reflections | Δρmin = −1.03 e Å−3 |
12 parameters | Absolute structure: 71 of Friedel pairs used in the refinement |
0 restraints | Absolute structure parameter: 0.05 (3) |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
x | y | z | Uiso*/Ueq | ||
Au | 0.875 | 0.875 | 0.875 | 0.0407 (2) | |
Te | 0.22938 (8) | 0.22938 (8) | 0.22938 (8) | 0.0286 (2) | |
Ag | −0.13818 (15) | 0 | 0.25 | 0.0392 (6) |
Atomic displacement parameters (Å2) top
U11 | U22 | U33 | U12 | U13 | U23 | |
Au | 0.0407 (4) | 0.0407 (4) | 0.0407 (4) | −0.0056 (4) | −0.0056 (4) | −0.0056 (4) |
Te | 0.0286 (4) | 0.0286 (4) | 0.0286 (4) | −0.0007 (4) | −0.0007 (4) | −0.0007 (4) |
Ag | 0.0464 (10) | 0.0382 (9) | 0.0329 (10) | 0 | 0 | 0.0052 (7) |
Geometric parameters (Å, º) top
Au—Tei | 2.6273 (13) | Te—Agx | 2.9825 (19) |
Au—Teii | 2.6273 (13) | Te—Agxi | 2.9825 (19) |
Au—Agiii | 3.0784 (18) | Te—Agxii | 2.9140 (18) |
Au—Agiv | 3.0784 (18) | Te—Agxiii | 2.9140 (18) |
Au—Agv | 3.0784 (18) | Te—Agxiv | 2.9140 (18) |
Au—Agvi | 3.0784 (18) | Ag—Agxv | 3.0814 (16) |
Au—Agvii | 3.0784 (18) | Ag—Agxvi | 3.0814 (16) |
Au—Agviii | 3.0784 (18) | Ag—Agxiv | 3.3053 (17) |
Te—Agix | 2.9825 (19) | Ag—Agxvii | 3.3053 (17) |
Tei—Au—Teii | 180 | Agxii—Te—Agxiv | 118.95 (4) |
Tei—Au—Agiii | 62.44 (3) | Agxiii—Te—Agxiv | 118.95 (4) |
Tei—Au—Agiv | 62.44 (3) | Auxix—Ag—Auxx | 73.48 (4) |
Tei—Au—Agv | 62.44 (3) | Auxix—Ag—Teix | 51.35 (2) |
Tei—Au—Agvi | 117.56 (3) | Auxix—Ag—Texxi | 96.55 (4) |
Tei—Au—Agvii | 117.56 (3) | Auxix—Ag—Texii | 140.40 (3) |
Tei—Au—Agviii | 117.56 (3) | Auxix—Ag—Texxii | 98.00 (3) |
Teii—Au—Agiii | 117.56 (3) | Auxix—Ag—Agxv | 83.95 (4) |
Teii—Au—Agiv | 117.56 (3) | Auxix—Ag—Agxvi | 59.97 (3) |
Teii—Au—Agv | 117.56 (3) | Auxix—Ag—Agxiv | 80.30 (2) |
Teii—Au—Agvi | 62.44 (3) | Auxix—Ag—Agxvii | 150.04 (4) |
Teii—Au—Agvii | 62.44 (3) | Auxx—Ag—Teix | 96.55 (4) |
Teii—Au—Agviii | 62.44 (3) | Auxx—Ag—Texxi | 51.35 (2) |
Agiii—Au—Agiv | 100.31 (3) | Auxx—Ag—Texii | 98.00 (3) |
Agiii—Au—Agv | 100.31 (3) | Auxx—Ag—Texxii | 140.40 (3) |
Agiii—Au—Agvi | 60.066 (13) | Auxx—Ag—Agxv | 59.97 (3) |
Agiii—Au—Agvii | 106.52 (3) | Auxx—Ag—Agxvi | 83.95 (4) |
Agiii—Au—Agviii | 148.96 (2) | Auxx—Ag—Agxiv | 150.04 (4) |
Agiv—Au—Agv | 100.31 (3) | Auxx—Ag—Agxvii | 80.30 (2) |
Agiv—Au—Agvi | 106.52 (3) | Teix—Ag—Texxi | 142.85 (6) |
Agiv—Au—Agvii | 148.96 (2) | Teix—Ag—Texii | 92.99 (3) |
Agiv—Au—Agviii | 60.066 (13) | Teix—Ag—Texxii | 108.03 (3) |
Agv—Au—Agvi | 148.96 (2) | Teix—Ag—Agxv | 57.41 (3) |
Agv—Au—Agvii | 60.066 (13) | Teix—Ag—Agxvi | 107.32 (4) |
Agv—Au—Agviii | 106.52 (3) | Teix—Ag—Agxiv | 54.93 (3) |
Agvi—Au—Agvii | 100.31 (3) | Teix—Ag—Agxvii | 148.43 (3) |
Agvi—Au—Agviii | 100.31 (3) | Texxi—Ag—Texii | 108.03 (3) |
Agvii—Au—Agviii | 100.31 (3) | Texxi—Ag—Texxii | 92.99 (3) |
Auxviii—Te—Agix | 66.21 (3) | Texxi—Ag—Agxv | 107.32 (4) |
Auxviii—Te—Agx | 66.21 (3) | Texxi—Ag—Agxvi | 57.41 (3) |
Auxviii—Te—Agxi | 66.21 (3) | Texxi—Ag—Agxiv | 148.43 (3) |
Auxviii—Te—Agxii | 95.92 (4) | Texxi—Ag—Agxvii | 54.93 (3) |
Auxviii—Te—Agxiii | 95.92 (4) | Texii—Ag—Texxii | 110.83 (6) |
Auxviii—Te—Agxiv | 95.92 (4) | Texii—Ag—Agxv | 59.59 (3) |
Agix—Te—Agx | 104.83 (4) | Texii—Ag—Agxvi | 159.29 (4) |
Agix—Te—Agxi | 104.83 (4) | Texii—Ag—Agxiv | 92.97 (4) |
Agix—Te—Agxii | 63.00 (3) | Texii—Ag—Agxvii | 56.89 (3) |
Agix—Te—Agxiii | 161.90 (5) | Texxii—Ag—Agxv | 159.29 (4) |
Agix—Te—Agxiv | 68.18 (3) | Texxii—Ag—Agxvi | 59.59 (3) |
Agx—Te—Agxi | 104.83 (4) | Texxii—Ag—Agxiv | 56.89 (3) |
Agx—Te—Agxii | 161.90 (5) | Texxii—Ag—Agxvii | 92.97 (4) |
Agx—Te—Agxiii | 68.18 (3) | Agxv—Ag—Agxvi | 135.58 (6) |
Agx—Te—Agxiv | 63.00 (3) | Agxv—Ag—Agxiv | 103.58 (4) |
Agxi—Te—Agxii | 68.18 (3) | Agxv—Ag—Agxvii | 95.42 (4) |
Agxi—Te—Agxiii | 63.00 (3) | Agxvi—Ag—Agxiv | 95.42 (4) |
Agxi—Te—Agxiv | 161.90 (5) | Agxvi—Ag—Agxvii | 103.58 (4) |
Agxii—Te—Agxiii | 118.95 (4) | Agxiv—Ag—Agxvii | 128.37 (5) |
Symmetry codes: (i) x+1/2, y+1/2, z+1/2; (ii) −y+5/4, −x+5/4, −z+5/4; (iii) −x+1/2, −y+1, z+1/2; (iv) z+1/2, −x+1/2, −y+1; (v) −y+1, z+1/2, −x+1/2; (vi) y+3/4, x+5/4, −z+5/4; (vii) x+5/4, z+3/4, −y+3/4; (viii) z+3/4, −y+3/4, x+5/4; (ix) −x, −y+1/2, z; (x) z, −x, −y+1/2; (xi) −y+1/2, z, −x; (xii) −y+1/4, −x+1/4, −z+1/4; (xiii) −x+1/4, z−1/4, y+1/4; (xiv) z−1/4, y+1/4, −x+1/4; (xv) y−1/4, x+1/4, −z+1/4; (xvi) −y−1/4, −x−1/4, −z+3/4; (xvii) z−1/4, −y−1/4, x+1/4; (xviii) x−1/2, y−1/2, z−1/2; (xix) −x+1/2, −y+1, z−1/2; (xx) −x+1/2, y−1, −z+1; (xxi) −x, y−1/2, −z+1/2; (xxii) −y+1/4, x−1/4, z+1/4. |