Images
Formula: Cu2S
Sulphide of copper, tetragonal
paramorph of monoclinic
chalcocite
Crystal system: Tetragonal
Specific gravity: 5.618 calculated for the average empirical formula
Hardness: 3
Streak: Black
Colour: Dark grey, becoming bluer and darker with increasing Fe content
Common impurities: Fe
Environments
Sedimentary environments
Hydrothermal environments
Wuyanzhiite is a relatively new mineral, approved in 2017 and to date (May 2026) reported only from the type
locality.
Localities
The type locality, the Baifang Mine, Changning County, Hengyang, Hunan, China, is a small-scale mine that has been
under production since 1960. It is famous for massive chalcocite ores, with
an average copper grade of about 35%, which are directly transported to the
copper smelter without ore dressing. Wuyanzhiite was found in these ores; associated minerals include
chalcocite, djurleite,
digenite, sphalerite,
tennantite-(Zn), bornite,
pyrite and smithsonite with the
presence of uraninite, arsenic,
zeunerite and kasolite.
Wuyanzhiite, along with other copper and
zinc sulphide and carbonate minerals, is considered to have been formed from
secondary enrichment of
copper at relatively high temperature (182°C–192°C) and low salinity.
Wuyanzhiite occurs as granular aggregates or oriented ribbons measuring 10 μm to more than 500 μm in size,
composed of nanometric to micrometric anhedral crystals. It often forms intimate intergrowth with
chalcocite, djurleite,
digenite, tennantite-(Zn)
and zeunerite. Macroscopically, it is dark grey with a metallic lustre and
a black streak
(AM 111.736–745).
Back to Minerals