Topaz

Fe_0.117Mg_6.217O₁₄Si₂

Holl, C. M.Smyth, J. R.Manghnani, M. H.Amulele, G. M.Sekar, M.Frost, D. J.Prakapenka, V. B.Shen, G.

Physics and Chemistry of Minerals (2006) 33, 192-199

a=7.8678Å   b=7.8678Å   c=9.5771Å

α=90°   β=90°   γ=120°