Olivine

Fe_0.19Mg_1.81O₄Si

McCormick, T. C.Smyth, J. R.Lofgren, G. E.

Physics and Chemistry of Minerals (1987) 14, 368-372

a=4.7641Å   b=10.2269Å   c=5.9952Å

α=90°   β=90°   γ=90°