Summary: Ranunculite occurs as gold-yellow nodules. Mean diameter = 0.3 mm. Optically biaxial negative, 2V (calc.) = 56°. γ =1.670, β = 1.664, and α = 1.643. Monoclinic, pseudo-orthorhombic with a = 11.1 Å, b = 17.7 Å, c = 18.0 Å, and β ⋍ 90°. Z = 14. Measured density = 3.4 g/cm³. Calculated density = 3.39 g/cm³. The strongest lines of the X-ray powder pattern are (d, hkl, I): 9.00, 002–020 (100), 3.133, 330 (80), 470, 202–220 (50), 2.978, 006–060 (40), and 1.850, 600 (40). Chemical analysis by electron microprobe: Al₂O₃ 9.9%, UO₃ 54.5%, P₂O₅ 13.2%, H₂O by thermogravimetry 20.3%. Formula: AlH(UO₂)(PO₄)(OH)₃ · 4H₂O. Ranunculite occurs at Kobokobo, Kivu, Zaire, in pegmatitic rocks. The name after the colour (ranunculus = buttercup).