X-ray characterization of Mg, Fe, and Mn natural end-members of the axinite group

New powder X-ray diffraction data for magnesio-, ferro-, and manganaxinite, obtained from samples closely corresponding to the three end-members of the axinite mineral group, were obtained using a conventional Bragg-Brentano diffractometer. Space group is P 1̄. Powder patterns were indexed using Peacock's normal orientation, which gave: a = 7.1381(3), b = 9.1626(4), c = 8.9421(4) Å, α = 91.903(4), β = 98.105(3), γ = 77.468(4)° for magnesioaxinite; a = 7.1479(4), b = 9.1962(5), c = 8.9576(4) Å, α = 91.857(4), β=98.177(4), γ = 77.359(4)° for ferroaxinite, and a = 7.1849(4), b = 9.2152(5), c = 8.9765(4) Å, α = 91.761(4), β = 98.153(4), γ = 77.150(4)° for manganaxinite. Peacock's orientation has been adopted in all recent structural and crystal chemical studies of axinite, but it differs from that reported on the JCPDS cards (29-344, 27-076 and 27-084, respectively). New data include an increased number of indexed peaks. © 2000 International Centre for Diffraction Data.