Manganese Ore - Restormel (#1215)
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Fact sheet
Description: 

Forming botryoidal growths (kidney-ore) this sample could easily be mistaken as iron ore, not least because it is from Restormel Royal mine which operated as an iron mine from at least 1797 until final closure in 1910. Between 1855 and 1883, 127,796 tons of iron ore were produced. However, as well as iron, the mine is also known for its manganese, bismuth, barium and uranium mineralisation.

Analysis has shown that the rich, dark brown ore in this sample is an intimate mixture of cryptomelane (a KMn oxide) and romanechite (a BaMn oxide). It's impossible to tell them apart optically.

Iron-manganese mineralisation occurs at low temperatures and marks the end of hydrothermal activity in the St Austell area.

See also Cotterell, T.F. (2010) An unusual manganese-bearing assemblage from Restormel, Lostwithiel, Cornwall. Journal of the Russell Society, 13, 53-56.

In Place
In Time
Accuracy:
Location precision: 
Moderate
Timescale:
Timescale: 
Permian
Ma = Millions of years ago
In Focus
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Type:
Type: 
mineral
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Rock-forming minerals:

Rock forming mineral:

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