The crystal structure of yeatmanite

Abstract

The crystal structure of yeatmanite [Mn₅Sb₂] ^VI[Zn₆Mn₄(Si_3.8Fe_0.2³⁺)] ^IVO₂₈; P-1, a = 5.443(3), b = 11.683(5), c = 9.134(4)Å, α = 92.06(4), β = 101.19(4), γ = 76.34(4)°, Z = 1] from Franklin, New Jersey, has been refined to an R = 0.100 using 1881 reflections. The structure scheme proposed by Moore et al. [(1916); Neues Jahrb. Abh., 127, 47–61] was proved to be correct. The octahedral sheet consisting of 5Mn and 2Sb is sandwiched by the upper and the lower tetrahedral sheets consisting of Zn₃Mn₂Si₂, respectively. Along the a-axis, there are two rows of Si tetrahedra, one of which is surrounded by 4ZnO₄ and 2MnO₄, and the other by 3ZnO₄ and 3MnO₄. A small portion of the latter is replaced by trivalent iron. The mean distances of M–O are as follows: Sb^VI–O 2.00 Mn(1)^VI–O 2.24, Mn(2)^VI–O 2.19, Mn(3)^VI–O 2.22, Mn(4)^VI–O 2.12, Mn(5)^IV–O 2.08, Zn(1)^IV–O 2.03, Zn(2)^IV–O 1.95, Zn(3)^IV–O 1.99, Si(1)^IV–O 1.64 and Si(2)^IV–O 1.66Å.