Coronadite

Crystal System: Monoclinic
Status of Occurrence: Confirmed Occurrence
Distribution: Rare
Chemical Composition: Lead manganese oxide
Chemical Formula: Pb(Mn4+)2(Mn2+)6O16
Method(s) of Verification: Lletty Evan-hen Mine - XRD and EDS at the National Museum of Wales (XRD numbers NMW X-1726 and X-1727).

Chemical Group:

  • Oxides & Hydroxides

Geological Context:

  • Supergene: in situ natural oxidation & weathering deposits
Soft, black, botryoidal coronadite crust from Lletty Evan-hen Mine, Penrhyncoch, Ceredigion. Specimen 9 cm long. National Museum of Wales specimen no. NMW 2007.42G.M.4a. © National Museum of Wales.
Concentric coronadite growths from Lletty Evan-hen Mine viewed in plane-polarized light. Field of view 0.7 mm across. Amgueddfa Cymru specimen no. NMW 2007.42G.M.5b. © National Museum of Wales.
Introduction: a secondary manganese mineral found in the oxidation zone above primary manganese- and lead-bearing mineral veins.
Occurrence in Wales: coronadite is one of number of base metal-bearing manganese oxides discovered in the Central Wales Orefield (Cotterell, 2009). So far it has only been identified at Lletty Evan-hen Mine, but with more research it will probably be found to occur at many more localities, albeit in small amounts.

Key Localities:

  • Lletty Evan-Hen Mine, Bont-goch, Ceredigion: coronadite is the dominant manganese oxide present on the main tips occurring as soft, black, botryoidal crusts on reddish to pink stained siltstone (Cotterell, 2009).

There are no key localities for this specimen.

References:

  1. Cotterell, T.F., 2009. Supergene manganese mineralization associated with the Camdwr Fault in the Central Wales Orefield. Journal of the Russell Society, 12, 15-25.

There are no references for this specimen.