Données cristallographiques sur le tétrachromate d'ammonium (NH₄)₂Cr₄O₁₃

(NH₄)₂Cr₄O₁₃ is monoclinic (P2₁/c, isotypic with K₂Cr₄O₁₃ and Rb₂Cr₄O₁₃, with a = 17.82 (1), b = 7.658 (4), c = 9.360 (3) Å, β = 92.00 (1)° , V = 1276 ų, Z = 4 and D_x = 2.35 Mg/m³.