Kenoargentotetrahedrite-(Fe) is observed as greenish-grey anhedral grains, 50–150 μm in size, in association with galena, sphalerite and chalcopyrite in the Bajiazi Pb-Zn deposit of magmatic-hydrothermal type, Liaoning, China. The empirical formula from electron microprobe analyses is Ag
5.50Cu
4.17Fe
1.75Zn
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Kenoargentotetrahedrite-(Fe) is observed as greenish-grey anhedral grains, 50–150 μm in size, in association with galena, sphalerite and chalcopyrite in the Bajiazi Pb-Zn deposit of magmatic-hydrothermal type, Liaoning, China. The empirical formula from electron microprobe analyses is Ag
5.50Cu
4.17Fe
1.75Zn
0.31Sb
3.96As
0.04S
12.08, corresponding to the ideal formula Ag
6Cu
4Fe
2Sb
4S
12. The crystal structure of kenoargentotetrahedrite-(Fe) has been determined and refined by single-crystal X-ray diffraction with R
1 = 0.0192 for 1866 (404 unique) reflections. It is cubic, space group
I3
m with unit cell parameters
a = 10.4928(2) Å,
V = 1155.26(7) Å
3 and
Z = 2. The structure of kenoargentotetrahedrite-(Fe) is characterized by a poor occupancy of 0.05 of the octahedral S(2) site with the S(2)-
M(2) bonding length of 1.9994(8) Å. The six Ag atoms at
M(2) around S(2) form an octahedron cluster (Ag
6)
4+ with the valence state of +4 and Ag-Ag distance of 2.8276(1) Å. The structure is identical to that by Rozhdestvenskaya et al., being composed of a collapsed sodalite-like framework of corner-connected
M(1)S
4 tetrahedron forming cages containing
M(2)
6-octahedron cluster, encircled by four SbS
3 trigonal pyramids. It is related to the tetrahedrite group minerals with the existence of the (Ag
6)
4+ cluster replacing the S(2)-centered Ag
6 octahedron according to the substitution mechanism 6
M(2)Ag
+ +
S(2)S
2−=
M(2)(Ag
6)
4+ +
S(2) S.
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