You can help expand this article with text translated from the corresponding article in German. Click [show] for important translation instructions. Machine translation, like DeepL or Google Translate, is a useful starting point for translations, but translators must follow the LLM translation guideline, revise errors as necessary and confirm that the translation is accurate, rather than simply copy-pasting machine-translated text into the English Wikipedia. Consider adding a topic to this template: there are already 1,885 articles in the main category, and specifying|topic= will aid in categorization. Do not translate text that appears unreliable or low-quality. If possible, verify the text with references provided in the foreign-language article. You must provide copyright attribution in the edit summary accompanying your translation by providing an interlanguage link to the source of your translation. A model attribution edit summary is Content in this edit is translated from the existing German Wikipedia article at [[:de:Fukuchilit]]; see its history for attribution. You may also add the template {{Translated|de|Fukuchilit}} to the talk page. For more guidance, see Wikipedia:Translation.

Fukuchilite
Fukuchilite
General
Category	Sulfide mineral
Formula	Cu3FeS8
IMA symbol	Fuk[1]
Strunz classification	2.EB.05a
Crystal system	Cubic
Crystal class	Diploidal (m3) H-M symbol: (2/m 3)
Space group	Pa3
Unit cell	a = 5.58 Å: Z = 1
Identification
Color	Dark brownish gray; pinkish brown in polished section
Crystal habit	As intergrowths with pyrite and covellite, grains less than 1 μm
Mohs scale hardness	4 - 6
Luster	Submetallic
Diaphaneity	Opaque
Specific gravity	4.86
Optical properties	Isotropic
References	[2][3][4]

Fukuchilite, Cu
₃FeS
₈, 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.^[5] 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.^[6]

It is in the isotropic cubic crystal system with symmetry: (2/m3), 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 (Cu,Ni,Co,Fe)S
₂,^[7] but fukuchilite currently still holds its mineral status as there is currently not enough evidence to discredit an already accepted and titled mineral.^[6]

References