Iyoite

MnCuCl(OH)3
IMA status
  • Approved
IMA symbol
Iy
IMA approved
2013
Also known as
  • IMA2013-130
  • Iyoiet

Where it forms, where it's found

Geological setting

Former Cu mine; in crevices of Mn ore containing native copper, as a result of reaction of seawater with the ore.

Type locality
Ohku mine
  1. Ikata (Sadamisaki Peninsula)
  2. Nishiuwa District
  3. Ehime Prefecture
  4. Japan

33.4117°, 132.1811°

1recorded occurrences
Source · OpenStreetMap

Physical

Colour
Pale green
Density
3.22 g/cm³

Crystallography

Crystal system
Monoclinic
Space group
P21/m
Cell parameters
a = 5.717(2) Å · b = 6.586(2) Å · c = 5.623(3) Å
Cell angles
β = 88.45(3) °
Ratio a:b:c
1 : 1.152 : 0.984
Unit cell volume
211.63 ų
Morphology

Radial and dendritic aggregates consisting of pale green, bladed crystals.

Type-locality form

Blades, in radial and dendritic aggregates

Comment

"same axial setting with botallackite"

Chemical composition

Constituent elements
Mass composition breakdown
ElementAtoms At. mass g/mol Mass g/molMass share
29CuCopperCopper163.54663.546
31.00%
25MnManganeseManganese154.93854.938
26.80%
8OOxygenOxygen315.99947.997
23.42%
17ClChlorineChlorine135.45035.450
17.30%
1HHydrogenHydrogen31.0083.024
1.48%
Total204.955100.00%

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

From IMA formula

Synonyms

  • IMA2013-130
  • Iyoiet

In other languages

German
IMA 2013-130 · Iyoit
Italian
iyoite

Classification

Strunz
10th ed.

3.DA.10b

  • 3HalidesClass
  • 3.DOxyhalides, hydroxyhalides and related double halidesDivision
  • 3.DAWith Cu, etc., without PbGroup
  • 3.DA.10bIyoiteSpecies

Group, growth & confusion

Literature, links & citation

Citations
  1. 2014Williams, P. A., Hatert, F., Pasero, M., Mills, S. J. (2014) New minerals and nomenclature modifications approved in 2014, CNMNC Newsletter No 20. Mineralogical Magazine, 78 (3) 549-558 doi:10.1180/minmag.2014.078.3.05DOI: 10.1180/minmag.2014.078.3.05
  2. 2017(2017) Iyoite. Handbook of Mineralogy. Mineralogical Society of America
  3. 2017Nishio–Hamane, D., Momma, K., Ohnishi, M., Shimobayashi, N., Miyawaki, R., Tomita, N., Okuma, R., Kampf, A. R., Minakawa, T. (2017) Iyoite, MnCuCl(OH)3 and misakiite, Cu3Mn(OH)6Cl2: new members of the atacamite family from Sadamisaki Peninsula, Ehime Prefecture, Japan. Mineralogical Magazine, 81 (3) 485-498 doi:10.1180/minmag.2016.080.104 DOI: 10.1180/minmag.2016.080.104
Cite this entry
@misc{mineral2026,
  author    = {Mineral Index editorial board},
  title     = {Iyoite — Mineral Index},
  year      = {2026},
  url       = {https://mineralindex.org/minerals/iyoite-45980},
  note      = {Accessed 2026-05-11}
}