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Formula: Cu2Fe(AsO4)(OH)4.4H2O
Hydrated arsenate containing hydroxyl, forms a series with
liroconite
Crystal System: Monoclinic
Specific gravity: 3.048 calculated
Colour: Emerald green
Environments
Kernowite was approved in November 2020.
Localities
The type locality is Wheal Gorland, St Day, Cornwall, England, UK, where it was found by curator Mike Rumsey on a museum
specimen that was collected 220 years ago.
It occurred as large emerald-green crystals associated with liroconite. The mine
was active between around 1790 and 1909, but it has been demolished now and there is a housing estate where the mine once
was. Hopefully other samples will be found in other public and private collections, but until that happens the one sample
held at the Natural History Museum London and another in a private collection are the only known examples of kernowite
in the entire world
(https://www.nhm.ac.uk/discover/news/2020/december/beautiful-new-emerald-green-mineral-described-from-cornwall.html).
Kernowite occurs on specimens from the cavities of a
quartz-gossan rich in undifferentiated
micro-crystalline grey sulphides and poorly crystalline arsenic phases including
both pharmacosiderite and
olivenite-group minerals
(MM 85.3.283-290).
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