Introduction:

manganite is a black, to dark steely-grey, manganese mineral with two polymorphs feitknechtite and groutite. It is usually found with other manganese minerals in low-temperature hydrothermal deposits, but is less common than psilomelane or pyrolusite.

Occurrence in Wales:

manganite has been noted from Wales on several occasions, but care should be taken with early references as some can confuse pyrolusite for manganite and vice versa. Hall (1868) listed manganite from the Gower, South Wales and Clynnog, Caernarvonshire, but provided almost no details of either occurrence. A specimen from this latter locality is present in the mineral collection of the Natural History Museum, London along with another from Benallt Mine also on Pen Llŷn. Williams (1927) described the presence of manganite in Ordovician-aged tuffs in the vicinity of Lliwedd, in Snowdonia. Specimens of crystallized manganese ore from near Beddgelert, not far from Lliwedd, have all proved to be pyrolusite (T.F. Cotterell, unpublished data).

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