Lithiophorite

Crystal System: Monoclinic
Status of Occurrence: Confirmed Occurrence
Distribution: Locally Abundant
Chemical Composition: Aluminium lithium manganese oxide hydroxide
Chemical Formula: (Al,Li)Mn4+O2(OH)2
Method(s) of Verification: Drosgol - XRD, EPMA & ore microscopy (National Museum of Wales, NMW X-1385, on specimen NMW 2002.22G.M.1); Moel Llyfnant - XRD (NMW X-1580 & 1581).

Chemical Group:

  • Oxides & Hydroxides

Geological Context:

  • Supergene: in situ natural oxidation & weathering deposits
Botryoidal lithiophorite from a vein outcrop near Drosgol Mine, Central Wales Orefield. National Museum of Wales Collection. Photo T.F. Cotterell, © National Museum of Wales.
Introduction: a secondary manganese mineral typically occurring in the oxidized zone of hydrothermal ore deposits and secondary manganese deposits. Lithiophorite is also a common constituent of soils.
Occurrence in Wales: lithiophorite is recorded in an unpublished report on analysis carried out by the Mineralogy and Petrology Research Group of BGS (Bain et al., 1968). The sample containing lithiophorite was from a locality on the east side of Drosgol near Ponterwyd, Ceredigion. Recent investigations looking at manganese mineralization in Wales (T.F. Cotterell, unpublished data) has uncovered several more localities for lithiophorite, with one particular site in the Arenig District of North Wales producing rich handspecimens of soft bluish-black feathery lithiophorite.

Key Localities:

  • Drosgol, Ponterwyd, Ceredigion: manganese mineralization consisting of minutely botryoidal bluish black lithiophorite is exposed in a gully below Drosgol Mine (T.F. Cotterell, unpublished data). Lithiophorite is typically developed enclosing quartz-coated bleached mudstone fragments within a highly altered vein breccia. Ore microscopy reveals the botryoids to be composed of minute platy crystals.
  • Moel Llyfnant, Arenig District, Gwynedd: rich masses of soft, bluish-black, feathery lithiophorite occur associated with cryptomelane in scree beneath remote trial workings near to the summit of Moel Llyfnant (T.F. Cotterell, unpublished data).

References:

  1. Bain, J.A., McKissock, G.M. and Livingstone, A., 1968. IGS Mineralogy Unit Rep. No. 1 (Unpublished).