Crystal data for the fluoroalleghanyite series n Mn 2 SiO 4 MnF 2 (1, n <4)

Unit‐cell constants for synthetic fluoroalleghanyite compounds have been determined by the refinement of X‐ray powder diffraction data. Manganese norbergite: Pbnm , a = 4.862(2), b = 10.797(3), c = 9.188(2) Å, U = 482.4(4) Å 3 , Z = 4; alleghanyite: P 2 1 / b , a = 4.871(2), b = 10.818(6), c = 8.206(5) Å, α = 108.58(5)°, U = 414.1(7) Å 3 , Z = 2; manganhumite: Pbnm , a = 4.888 (2), b = 10.712(2), c = 21.749(6), U = 1138.8(5) Å 3 , Z = 4; sonolite: P 2 1 / b , a = 4.889(1), b = 10.668(3), c = 14.239(5), α = 100.83(5)°, U = 731.9(5) Å 3 , Z = 2. The JCPDS Powder Diffraction File numbers are: for manganese norbergerite 33–1500; for alleghanyite 33–1499; for manganhumite 33–1498; for sonolite 33–1497.