Digenite
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Digenite is named from the Greek word "digenus" meaning "of two origins" or "sexes", because of it's relationship to Chalcocite and Covellite due to the presumed presence of both cuprous and cupric ions.

Discovered in 1844;   IMA status:  Valid (pre-IMA; Grandfathered)

Chemistry

Chemical Formula:

Cu₉S₅

Copper Sulfide

Molecular Weight:

732.24 gm

Composition:

Copper

78.10 %

Cu

Sulfur

21.90 %

S

100.00 %

Classification

Mineral Classification:

Sulfides

Strunz 8th Ed. ID:

2/B.01-30

Nickel-Strunz 10th Ed. ID:

2.BA.10

2 : SULFIDES and SULFOSALTS (sulfides, selenides, tellurides; arsenides, antimonides, bismuthides; sulfarsenites, sulfantimonites, sulfbismuthites, etc.)
B : Metal Sulfides, M: S > 1: 1 (mainly 2: 1)
A : With Cu, Ag, Au

Related to:

Chalcocite-Digenite Group. Digenite-Berzelianite Series.

Varieties:

None

Synonyms:

α-Chalcocite, Blue Chalcocite, Carmenite, Isometric Chalcocite, Kupferglanz-α, Neodigenite

Crystal Data

Crystallography:

Trigonal - Hexagonal Scalenohedral

Crystal Habit:

Rarely in pseudocubic crystals, to 3 cm; more commonly as intergrowths with other copper sulfides.

Twinning:

None

Physical Properties

Cleavage:

Distinct/Good on {111} (on synthetic material)

Fracture:

Conchoidal

Tenacity:

Brittle

Moh's Hardness:

2.5 - 3.0

Density:

5.546 (g/cm³)

Luminescence:

None

Radioactivity:

Not Radioactive

Optical Properties

Color:

Blue to Black; distinctly Blue in polished section.

Transparency:

Opaque

Luster:

Metallic

Refractive Index:

R: (400) 29.6, (420) 28.8, (440) 28.0, (460) 27.0, (480) 25.9, (500) 24.8, (520) 23.5, (540) 22.2, (560) 21.0, (580) 19.9, (600) 18.9, (620) 18.0, (640) 17.2, (660) 16.3, (680) 15.5, (700) 14.8

Birefringence:

0.000  (mostly Isotropic)

Pleochroism:

None

Anisotrophism:

Mostly Isotropic. Color in reflected light: Blue

Occurances

Geological Setting:

In hydrothermal copper deposits of primary and secondary origin. Formed under a wide range of conditions; reported from mafic intrusives, as a volcanic exhalation product, and in pegmatites.

Common Associations:

Chalcocite, Djurleite, Bornite, Chalcopyrite, other copper minerals, Pyrite.

Common Impurities:

Fe

Type Locality:

Copper slate deposits, Sangerhausen, Saxony-Anhalt, Germany

Year Discovered:

1844

View mineral photos:

Digenite Mineral Photos and Locations

More Information

Mindat.org
Webmineral.com

Digenite is a rare copper sulfide mineral that is an important ore of Copper. It is not well know by mineral or gem collectors due to the lack of good crystal formations, lack of brilliant colors and it is easily confused with other copper sulfides. Despite these facts, faceted gems can be attractive with deep blue or black colors and metallic luster.

Digenite is named from the Greek word "digenus" meaning "of two origins" or "sexes", because of it's relationship to Chalcocite and Covellite due to the presumed presence of both cuprous and cupric ions. Digenite is found in copper sulfide deposits and is typically associated with and often intergrown with Chalcocite, Covellite, Djurleite, Bornite, Chalcopyrite and Pyrite. The type locality is Sangerhausen, Thuringia, Germany, in copper slate deposits.

Digenite is found at only a handful of localities worldwide. From Sangerhausen, Thuringia, Germany [TL]. In the Botallack mine, St. Just, Cornwall, and from Seathwaite Tarn, near Coniston, Cumbria, England. At Listulli, Norway. From Kiruna, Sweden. In the USA, crystallized at Butte, Silver Bow County, Montana; in Arizona, from the United Verde mine, Jerome, Yavapai County, the Magma mine, Superior, Pinal County, and at Bisbee, Cochise County. Abundant at Kennicott, Alaska. From Cananea, Sonora, Mexico. In Namibia, at Tsumeb. At Dongxiang, Jiangxi Province, China. Probably not yet recognized at many other localities.
 

  
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