Domeykite
Current inventory: 0 gems
 

  
Domeykite was named in 1845 by Wilhelm Haidinger in honor of the Polish-Chilean mineralogist Ignacy "Ignacio" Domeyko (1802-1889). who was the head (rector) of the University of Chile from 1867 to 1883.

Discovered in 1845; IMA status: Valid (pre-IMA; Grandfathered)

Chemistry

Chemical Formula:

Cu₃As

Copper Arsenide

Molecular Weight:

265.56 gm

Composition:

Copper

71.79 %

Cu

Arsenic

28.21 %

As

100.00 %

Classification

Mineral Classification:

Sulfides

Strunz 8th Ed. ID:

2/A.01-20

Nickel-Strunz 10th Ed. ID:

2.AA.10b

2 : SULFIDES and SULFOSALTS (sulfides, selenides, tellurides; arsenides, antimonides, bismuthides; sulfarsenites, sulfantimonites, sulfbismuthites, etc.)
A : Alloys
A : Alloys of metalloids with Cu, Ag, Au

Related to:

n/a

Varieties:

Argentodomeykite, Condurrite

Synonyms:

Arsenical Copper, Arsenical copper pyrites, ICSD 100149, PDF 44-1475

Crystal Data

Crystallography:

Isometric - Hextetrahedral

Crystal Habit:

Reniform, botryoidal; massive.

Twinning:

None

Physical Properties

Cleavage:

None

Fracture:

Irregular/Uneven

Tenacity:

Brittle

Moh's Hardness:

3.0 - 3.5; Vickers: VHN₁₀₀= 213 - 235 kg/mm²

Density:

7.20 - 7.29 (g/cm³)

Luminescence:

None

Radioactivity:

Not Radioactive

Optical Properties

Color:

Tin-white to steel-gray, tarnishes pale yellow, then pale brown, and finally to iridescence.

Transparency:

Opaque

Luster:

Metallic

Refractive Index:

R: (400) 41.1, (420) 41.4, (440) 41.7, (460) 43.1, (480) 45.2, (500) 47.5, (520) 49.3, (540) 50.7, (560) 52.2, (580) 53.6, (600) 54.5, (620) 54.9, (640) 54.8, (660) 54.6, (680) 54.4, (700) 54.6 R1–R2: (“domeykite-beta”): (400) 37.2–38.5, (420) 37.9–39.5, (440) 38.6–40.9, (460) 40.2–43.1, (480) 42.4–45.5, (500) 44.2–47.3, (520) 45.4–48.6, (540) 45.9–49.4, (560) 45.9–49.6, (580) 45.8–49.7, (600) 45.5–49.5, (620) 45.2–49.2, (640) 44.8–48.9, (660) 44.4–48.4, (680) 44.0–48.0, (700) 43.6–47.6

Birefringence:

0.000 (Isotropic)

Dispersion:

n/a

Pleochroism:

n/a

Anisotropism:

None

Occurances

Geological Setting:

Hydrothermal veins

Common Associations:

Copper (typically arsenian), Silver, Algodonite

Common Impurities:

Sb, S

Type Locality:

Los Algodones Mine, Los Algodones district, El Arrayan, La Serena, Elqui Province, Coquimbo Region, Chile

Year Discovered:

1845

View mineral photos:

Domeykite Mineral Photos and Locations

More Information

Mindat.org
Webmineral.com

Domeykite is a copper arsenide mineral that is frequently associated with Algodonite and other copper arsenides and often found as a mixture of these minerals, creating Mohawkite. Mohawkite is a mixture of Algodonite, Domeykite, arsenic-rich Copper and may also contain other minerals such as silver, cobalt, nickel or iron. Mohawkite is not considered a valid mineral species because it is a mixture, or alloy-like coumpound. Mohawkite is often mixed with Quartz crystal clusters as seen in the picture at the top of this page. This makes for a very attractive cabochon with bright, metallic, brassy Mohawkite and bright white Quartz. Cabochons of Algodonite, Domeykite and Mohawkite are bright and attractive with metallic luster but will tarnish quickly and turn a drab brown and lose their luster. They must be coated with lacquer or other protective coating to prevent tarnishing. Faceted gems are beautiful when cut and polished to a high luster but are very rarely available. Algodonite and Domeykite are heat sensitive, and care must be exercised when cutting.

Domeykite was named in 1845 by Wilhelm Haidinger in honor of the Polish-Chilean mineralogist Ignacy "Ignacio" Domeyko (1802-1889). who was the head (rector) of the University of Chile from 1867 to 1883. Mohawkite is named after the originally reported, and only, locality at the Mohawk Mine, Mohawk, Keweenaw County, Michigan, USA.

Domeykite distribution: in Chile, from the Type Locality at the Los Algodones silver mine, near Coquimbo and at San Antonio and Chañarcillo, near Copiapó, Atacama. From Corocoro, Bolivia. At Cerro de Paracatas, Tlachapa, Guerrero, Mexico. In the USA, from the Mohawk and Ahmeek mines, Keweenaw County, and in the Sheldon-Columbia mine, Portage Lake, Houghton County, Michigan; at the Cashin mine, Montrose County, Colorado; from Franklin, Sussex County, New Jersey. In Canada, on Michipicoten Island and at the Silver Islet mine, Thunder Bay, Lake Superior, Ontario; in the East Arm area, Great Slave Lake, Northwest Territories. From Långban and at the Harstigen mine, Värmland, Sweden. From Wasserfall, about 20 km northwest of Belfort, Haute-Saône, and at the Roua copper mines, about 50 km north of Nice, Alpes Maritimes, France. From Zwickau, Saxony, and at Sailauf, northeast of Aschaffenburg, Bavaria, Germany. In the Condurrow mine, near Helstone, Cambourne, and at Wheal Druid, Redruth, Cornwall, England. In the Talmessi mine, 35 km west of Anarak, Iran. Several other occurrences are known.
 

  
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