Cuprite
Current inventory:  0 gems
 

  
Cuprite was named in 1845 by Wilhelm Karl von Haidinger from the Latin word cuprum, meaning copper, in allusion to its composition. Haidinger renamed a previously known mineral that had been known by a wide variety of names.

Possibly discovered as early as 1546; IMA status: Valid (pre-IMA; Grandfathered)

Chemistry

Chemical Formula:

Cu₂O

Copper Oxide

Molecular Weight:

143.09 gm

Composition:

Copper

88.82 %

Cu

100.00 %

Cu₂O

Oxygen

11.18 %

O

100.00 %

100.00 %

= TOTAL OXIDE

Classification

Mineral Classification:

Oxides

Strunz 8th Ed. ID:

4/A.02-10

Nickel-Strunz 10th Ed. ID:

4.AA.10

4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
A : Metal: Oxygen = 2:1 and 1:1
A : Cation:Anion (M:O) = 2:1 (and 1.8:1)

Related to:

n/a

Varieties:

Chalcotrichite, Tile ore

Synonyms:

ICSD 63281, Hepatinerz (of Breithaupt), Kupferglas, Octahedral Copper, Octahedral Copper Ore, Oxydulated Copper, PDF 5-667, Red Copper, Red Glassy Copper Ore, Red oxide of Copper, Ruberite, Ruby Copper 

Crystal Data

Crystallography:

Isometric - Hexoctahedral 

Crystal Habit:

As cubic, octahedral, and dodecahedral crystals, to 14 cm, which may be highly modified; as hairlike capillary forms, with square section, reticulated, tufted and matted; also earthy, compact granular, massive. 

Twinning:

Penetration twins common

Physical Properties

Cleavage:

Interrupted on {111}, more rarely on {001}

Fracture:

Conchoidal, irregular/uneven

Tenacity:

Brittle

Moh's Hardness:

3.5 - 4.0; Vickers: VHN₁₀₀=183 - 222 kg/mm²  

Density:

6.14 g/cm³ (measured)

Luminescence:

None

Radioactivity:

Not Radioactive

Optical Properties

Color:

Cochineal-red, ruby-red, purplish red, to nearly black; in transmitted light, cochineal-red or red in thick sections; yellow-orange, yellow, lemon-yellow in progressively thinner sections; in reflected light, gray blue, commonly with many red internal reflections

Transparency:

Transparent to translucent

Luster:

Adamantine to submetallic, earthy

Refractive Index:

2.849  Isotropic

Birefringence:

0.000 (Isotropic)

Dispersion:

n/a

Pleochroism:

Anomalous, common

Anisotropism:

Anomalously anisotropic. Color in reflected light: bluish white. Internal reflections: blood-red.

Occurances

Geological Setting:

A common mineral in the oxidized portions of many copper deposits.

Common Associations:

Copper, Tenorite, Malachite, Azurite, Calcite, Brochantite, Antlerite, Atacamite, Chrysocolla, iron oxides, clay minerals

Common Impurities:

n/a

Type Locality:

Unknown

Year Discovered:

Possibly discovered as early as 1546.

View mineral photos:

Cuprite Mineral Photos and Locations

More Information

Mindat.org
Webmineral.com

Cuprite is a very rare and beautiful gem with a very high refractive index, adamantine luster and deep red color. Gem grade crystals mostly come from one location: Onganja mine, Namibia. Prior to this find, Cuprite gems were almost non-existant. There are a few other locations but crystals are typically very small. Most crystals on the market from Onganja are obtained by mineral collectors and are not used to cut gems. This makes Cuprite gems even rarer.

Cuprite is commonly found as an oxidation product of copper sulphides in the upper zones of veins and often associated with Azurite, Chalcocite, Native Copper, Limonite and Malachite. A fibrous form of Cuprite is known as Chalcotrichite. Cuprite crystals and gems may be so dark red as to look almost black but when properly lit can show a truely amazing ruby or blood red color.

Cuprite was named in 1845 by Wilhelm Karl von Haidinger from the Latin word cuprum, meaning copper, in allusion to its composition. Haidinger renamed a previously known mineral that had been known by a wide variety of names. The earliest reference to Cuprite may have been in 1546 by the German name Lebererzkupfer, meaning liver ore copper. Other previous names were: Hepatinerz (of Breithaupt), Kupferglas, Ruberite, Ruby Copper and Ziegelerz.

Cuprite distribution: A few localities for fine specimens include: at Bogoslovsk, Nizhni Tagil, and Yekaterinburg (Sverdlovsk), Ural Mountains, Russia. At Dzhezkazgan, Kazakhstan. In England, fine crystals from many mines in Cornwall. At Rheinbreitbach, North Rhine-Westphalia, Germany. In Namibia, large crystals from the Onganja mine, 60 km northeast of Windhoek, and at Tsumeb. At Likasi, Ruwe, and the Mashamba West mine, Kolwezi, Katanga Province, Congo (Shaba Province, Zaire). In the USA, in Arizona, large crystals from Bisbee, Cochise County, at Ray, Pinal County, Globe, Gila County, and elsewhere; from Santa Rita, Grant County, New Mexico. From Boleo, Baja California, Mexico. At Chuquicamata, Antofagasta, Chile. In Australia, from Broken Hill and Cobar, New South Wales; at Burra-Burra and Moonta, South Australia; large crystals in the Red Dome mine, Chilliago, Queensland.
 

  
Cuprite gems for sale: