Guanacoite

As₂Cu_2.582H₁₂Mg_2.418O₁₆

Witzke, T.Kolitsch, U.Krause, W.Wiechowski, A.Medenbach, O.Kampf, A. R.Steele, I. M.Favreau, G.

European Journal of Mineralogy (2006) 18, 813-821

a=5.475Å   b=16.865Å   c=6.915Å

α=90°   β=99.80°   γ=90°