Fukuchilite
title: "Fukuchilite" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["copper-minerals", "iron-minerals", "pyrite-group", "cubic-minerals", "minerals-in-space-group-205"] topic_path: "general/copper-minerals" source: "https://en.wikipedia.org/wiki/Fukuchilite" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0
::data[format=table title="Infobox mineral"]
| Field | Value |
|---|---|
| name | Fukuchilite |
| image | Fukuchilite displayed at Mining Museum of Akita University.jpg |
| alt | sample of fukuchilite |
| caption | Fukuchilite |
| category | Sulfide mineral |
| formula | Cu3FeS8 |
| IMAsymbol | Fuk |
| strunz | 2.EB.05a |
| system | Cubic |
| class | Diploidal (m) |
| H-M symbol: (2/m ) | |
| symmetry | Pa3 |
| unit cell | a = 5.58 Å: Z = 1 |
| color | Dark brownish gray; pinkish brown in polished section |
| habit | As intergrowths with pyrite and covellite, grains less than 1 μm |
| mohs | 4 - 6 |
| luster | Submetallic |
| diaphaneity | Opaque |
| gravity | 4.86 |
| opticalprop | Isotropic |
| references | |
| :: |
| name = Fukuchilite | image = Fukuchilite displayed at Mining Museum of Akita University.jpg | alt = sample of fukuchilite | caption = Fukuchilite | category = Sulfide mineral | formula = Cu3FeS8 | IMAsymbol = Fuk | strunz = 2.EB.05a | dana = | system = Cubic | class = Diploidal (m) H-M symbol: (2/m ) | symmetry = Pa3 | unit cell = a = 5.58 Å: Z = 1 | color = Dark brownish gray; pinkish brown in polished section | habit = As intergrowths with pyrite and covellite, grains less than 1 μm | twinning = | cleavage = | fracture = | tenacity = | mohs = 4 - 6 | luster = Submetallic | streak = | diaphaneity = Opaque | gravity = 4.86 | density = | polish = | opticalprop = Isotropic | refractive = | birefringence = | pleochroism = | 2V = | dispersion = | extinction = | length fast/slow = | fluorescence = | absorption = | melt = | fusibility = | diagnostic = | solubility = | impurities = | alteration = | other = | prop1 = | prop1text = | references =
Fukuchilite, , is a copper iron sulfide named after the Japanese mineralogist Nobuyo Fukuchi (1877–1934), that occurs in ore bodies of gypsum-anhydrite at the intersection points of small masses of barite, covellite, gypsum and pyrite, and is mostly found in the Hanawa mine in the Akita prefecture of Honshū, Japan where it was first discovered in 1969. It occurs in masses within the third geologic unit of the Kuroko type deposits within the mine.
As a copper, iron sulfide, it is placed in the same group as bornite and chalcopyrite, and most fukuchilite locations are found in relatively close proximity to these minerals. Fukuchilite was found to have a reflection color very similar to bornite and bright pinkish brown in air, while being a purplish brown in oil. Also, it was found to have a reactivity lower than pyrite, but distinctly higher than bornite. It has a Mohs hardness of 4–6, a specific gravity of 4.9, and a sub metallic luster, composed of 11.1% iron, 37.9% copper, and 51.00% of sulfur.
It is in the isotropic cubic crystal system with symmetry: (2/m), space group P a3. Much relating to the structure of the mineral is still under debate, and some believe that fukuchilite might actually be a form of villamaninite , but fukuchilite currently still holds its mineral status as there is currently not enough evidence to discredit an already accepted and titled mineral.
References
- Terakado, Yasutaka, and Richard J. Walker. "Nd, Sr and Pb Isotopic and REE Geochemical Study of Some Miocene Submarine Hydrothermal Deposits (Kuroko Deposits) in Japan." Contributions to Mineralogy and Petrology 149 (2005): 388-399
References
- Warr, L.N.. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine.
- [http://www.mindat.org/min-1620.html Fukuchilite on Mindat.org]
- [https://rruff.info/doclib/hom/fukuchilite.pdf Fukuchilite in the Handbook of Mineralogy]
- [https://www.webmineral.com/data/Fukuchilite.shtml Fukuchilite data on Webmineral]
- Kajiwara, Yoshimichi. "Fukuchilite, Cu3FeS8, a New Mineral From the Hanawa Mine, Akita Prefecture, Japan." Mineralogical Journal 5 (1969): 400-415.
- Bayliss, Peter. "Crystal Chemistry of Some Minerals Within the Pyrite Group." American Mineralogist 74 (1989): 1168-1176
- [https://webmineral.com/data/Villamaninite.shtml Villamaninite Mineral Data]
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