Jarosite

Fe_2.856H_6.73Na_0.75O₁₄S₂

Scarlett, N. V. Y.Grey, I. E.Brand, H. E. A.

American Mineralogist (2010) 95, 1590-1593

a=12.74852Å   b=7.34697Å   c=6.98243Å

α=90°   β=127.1974°   γ=90°