Crystal System: Hexagonal
Status of Occurrence: Confirmed Occurrence - 3rd UK recording
Chemical Composition: Hydrated manganese oxide with calcium
Chemical Formula: (Ca,Mn2+)Mn4+4O9.3H2O
Method(s) of Verification: identification of ranciéite is by XRD (no. NMW X-1552) and EDS (Cotterell and Jenkins, 2008).
- Oxides & Hydroxides
- Supergene: post-mining oxidation & weathering deposits
Introduction: a weathering product of manganese deposits and manganese-bearing minerals, particularly in Ca-rich environments such as limestones. A solid solution series exists between ranciéite and takanelite.
Occurrence in Wales: the only account of ranciéite in Wales was made by Cotterell and Jenkins (2008) who reported the mineral occurring as stalactites in the main drainage adit at Parys Mountain, Anglesey.
- Parys Mountain, Anglesey: rancieite occurs as small (< 10 cm) stalactites within the Joint (45 fm.) level at Mynydd Parys as reported by Cotterell and Jenkins (2008).
- Cotterell, T.F. & Jenkins, D.A., 2008. Ranciéite from Mynydd Parys, Amlwch, Anglesey, Wales. Journal of the Russell Society, 11, 59-63.