Ezochiite

Cu+(Rh3+Pt4+)S4
IMA status
  • Approved
  • Pending publication
IMA symbol
Ezo
Also known as
  • Ezochiiet

Where it forms, where it's found

Geological setting

in melt pockets in isoferroplatinum; not rare: found in various other geological environments, including in ophiolites, Ural–Alaskan intrusions and mafic–ultramafic intrusions

Type locality
Tomamae coast
  1. Tomamae
  2. Tomamae District
  3. Rumoi Subprefecture
  4. Hokkaidō Prefecture
  5. Japan

44.2858°, 141.6494°

2recorded occurrences
Source · OpenStreetMap

Physical

Hardness
123456789105/ 10 MOHS
  1. 1Talc
  2. 2Gypsum
  3. 3Calcite
  4. 4Fluorite
  5. 5Apatite
  6. 6Orthoclase
  7. 7Quartz
  8. 8Topaz
  9. 9Corundum
  10. 10Diamond
Transparency
Opaque
Density
6.66 g/cm³

Optical

Optical colour
bluish gray
Isotropy testPPL ↔ XPL diagnostic
PPL intrinsic colour; no change on stage rotation
XPL extinct at every orientation

Crystallography

Crystal system
Isometric
Space group
#222
Cell parameters
a = 9.865(4) Å
Type-locality form

anhedral grains < 5 µm in length

Chemical composition

Constituent elements
Mass composition breakdown
ElementAtoms At. mass g/mol Mass g/molMass share
78PtPlatinumPlatinum1195.084195.084
39.83%
16SSulfurSulfur432.060128.240
26.18%
45RhRhodiumRhodium1102.906102.906
21.01%
29CuCopperCopper163.54663.546
12.98%
Total489.776100.00%

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

From IMA formula

Synonyms

  • Ezochiiet

In other languages

German
Ezochiit · IMA 2022-101
Italian
Ezochiite

Classification

Strunz
10th ed.

2.DA

  • 2Sulfides and SulfosaltsClass
  • 2.DMetal Sulfides, M: S = 3 :4 and 2:3Division
  • 2.DAM:S = 3:4Group
  • 2.DAEzochiiteSpecies

Group, growth & confusion

Literature, links & citation

Citations
  1. 2023Bosi, Ferdinando; Miyawaki, Ritsuro; Hatert, Frédéric; Pasero, Marco; Mills, Stuart J. (2023) IMA Commission on New Minerals, Nomenclature and Classification (CNMNC) – Newsletter 71. European Journal of Mineralogy, 35 (1). 75-79 doi:10.5194/ejm-35-75-2023 DOI: 10.5194/ejm-35-75-2023
  2. 2024NISHIO-HAMANE, Daisuke, SAITO, Katsuyuki (2024) Ezochiite, Cu+(Rh3+Pt4+)S4, a new mineral in the thiospinel group from Hokkaido, Japan. Journal of Mineralogical and Petrological Sciences, 119 (1). 240304 doi:10.2465/jmps.240304DOI: 10.2465/jmps.240304
  3. 2025Cabri, Louis J.; McDonald, Andrew M. (2025) Ezochiite and shiranuiite are cuprorhodsite and are not new mineral species. American Mineralogist, 110 (6). 941-944 doi:10.2138/am-2024-9517DOI: 10.2138/am-2024-9517
Cite this entry
@misc{mineral2026,
  author    = {Mineral Index editorial board},
  title     = {Ezochiite — Mineral Index},
  year      = {2026},
  url       = {https://mineralindex.org/minerals/ezochiite-470612},
  note      = {Accessed 2026-05-11}
}