gsminmag Mineralogical Magazine Mineralogical Magazine 0026-461X Mineralogical Society 10.1180/minmag.1979.043.327.01 Ranunculite, AlH(UO2)(PO4)(OH)3 · 4H2O, a New Mineral1 Dellens Michel Département de Géologie et de Minéralogie, Musée royal de l'Afrique centrale, B 1980 Tervuren, Belgium Piret Paul Laboratoire de Chimie physique et de Cristallographie de l'Université, B 1348 Louvain-la-Neuve, Belgium

This paper is part III of the series ‘The uranyl and aluminium phosphates from Kobokobo’ (Deliens and Piret, 1977, 1979a, b).

 9 1979 43 327 321 323 15 12 1978 Copyright © 1979, The Mineralogical Society 1979 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).