Kernowite

Cu2Fe3+(AsO4)(OH)4 · 4H2O
IMA status
  • Approved
IMA symbol
Knw
IMA approved
2020
Also known as
  • IMA2020-053
  • Kernowiet

Where it forms, where it's found

Type locality
Wheal Gorland
  1. St Day
  2. Cornwall
  3. England
  4. UK

50.2417°, -5.1839°

1recorded occurrences
Source · OpenStreetMap

Safety & handling

Physical

Colour
Emerald-green
Density
3.048 g/cm³

Crystallography

Crystal system
Monoclinic
Cell parameters
a = 12.9243(4) Å · b = 7.5401(3) Å · c = 10.0271(3) Å
Cell angles
β = 91.267(3) °
Ratio a:b:c
1 : 0.583 : 0.776
Z
4
Comment

Spacegroup: I2∕a

Chemical composition

Constituent elements
Mass composition breakdown
ElementAtoms At. mass g/mol Mass g/molMass share
8OOxygenOxygen1215.999191.988
41.56%
29CuCopperCopper263.546127.092
27.51%
33AsArsenicArsenic174.92274.922
16.22%
26FeIronIron155.84555.845
12.09%
1HHydrogenHydrogen121.00812.096
2.62%
Total461.943100.00%

Mass share = atoms × atomic mass ÷ molar mass × 100

From IMA formula

Synonyms

  • IMA2020-053
  • Kernowiet

In other languages

German
IMA 2020-053 · Kernowit

Classification

Strunz
10th ed.

8.DF

  • 8Phosphates, Arsenates, VanadatesClass
  • 8.DPhosphates, etc. with additional anions, with H2ODivision
  • 8.DFWith only medium-sized cations, (OH,etc.):RO4 > 3:1Group
  • 8.DFKernowiteSpecies

Group, growth & confusion

Often grow together
1 mineral

Literature, links & citation

Citations
  1. 2020www.nhm.ac.uk (n.d.) https://www.nhm.ac.uk/discover/news/2020/december/beautiful-new-emerald-green-mineral-described-from-cornwall.html
  2. 2020www.bbc.co.uk (n.d.) https://www.bbc.co.uk/news/uk-england-cornwall-55396421
  3. 2020Miyawaki, Ritsuro, Hatert, Frédéric, Pasero, Marco, Mills, Stuart J. (2020) IMA Commission on New Minerals, Nomenclature and Classification (CNMNC) – Newsletter 58. European Journal of Mineralogy, 32 (6) 645-651 doi:10.5194/ejm-32-645-2020 DOI: 10.5194/ejm-32-645-2020
  4. 2021Rumsey, Michael S., Welch, Mark D., Spratt, John, Kleppe, Annette K., Števko, Martin (2021) Kernowite, Cu2Fe(AsO4)(OH)4⋅4H2O, the Fe3+-analogue of liroconite from Cornwall, UK. Mineralogical Magazine, 85 (3) 1-8 doi:10.1180/mgm.2021.40DOI: 10.1180/mgm.2021.40
  5. 2022(2022) Kernowite. Handbook of Mineralogy. Mineralogical Society of America
Cite this entry
@misc{mineral2026,
  author    = {Mineral Index editorial board},
  title     = {Kernowite — Mineral Index},
  year      = {2026},
  url       = {https://mineralindex.org/minerals/kernowite-55136},
  note      = {Accessed 2026-05-11}
}