Aurichalcite
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Aurichalcite is named from Aurichalcum, the Latinicized version of the Greek word oreichalchos meaning mountain copper.

Discovered in 1839; IMA status: Valid (pre-IMA; Grandfathered)

Chemistry

Chemical Formula:

(Zn,Cu)₅(CO₃)₂(OH)₆

Zinc Copper Carbonate Hydroxide

Molecular Weight:

546.71 gm

Composition:

Zinc

44.85 %

Zn

55.83 %

ZnO

Copper

14.53 %

Cu

18.19 %

CuO

Hydrogen

1.11 %

H

9.89 %

H₂O

Carbon

4.39 %

C

16.10 %

CO₂

Oxygen

35.12 %

O

100.00 %

100.00 %

= TOTAL OXIDE

Classification

Mineral Classification:

Carbonates

Strunz 8th Ed. ID:

5/C.01-110

Nickel-Strunz 10th Ed. ID:

5.BA.15

5 : CARBONATES (NITRATES)
B : Carbonates with additional anions, without H₂O
A : With Cu, Co, Ni, Zn, Mg, Mn

Related to:

n/a

Varieties:

None

Synonyms:

Auricalcite, Auricalcocita, Aurichalcita, Blue Calamine, Buratite, Messingite, Orichalcite, Risséite

Crystal Data

Crystallography:

Monoclinic - Prismatic

Crystal Habit:

As acicular to lathlike crystals with prominent {010}, commonly striated || [001], with wedgelike terminations, to 3 cm. Typically in tufted divergent sprays or spherical aggregates, may be in thick crusts; rarely columnar, laminated or granular.

Twinning:

Observed in X-ray patterns.

Physical Properties

Cleavage:

Perfect on {010} and {100}

Fracture:

Irregular/Uneven

Tenacity:

Fragile

Moh's Hardness:

1.0 - 2.0

Density:

3.96 (g/cm³)

Luminescence:

None

Radioactivity:

Not Radioactive

Other:

Soluble in acids and in ammonia.

Optical Properties

Color:

Pale green, greenish blue, sky-blue; colorless to pale blue, pale green in transmitted light.

Transparency:

Transparent

Luster:

Silky to Pearly

Refractive Index:

1.655 - 1.744  Biaxial ( - ) 

Birefringence:

0.089

Dispersion:

Relatively strong; r < v

Pleochroism:

Weak; X = Colourless, Y = Blue-green, Z = Blue-green

Occurances

Geological Setting:

A secondary mineral in oxidized zones of copper and zinc deposits, typically as crusts.

Common Associations:

Rosasite, Smithsonite, Hemimorphite, Hydrozincite, Malachite, Azurite

Common Impurities:

Ca

Type Locality:

Loktevskoye (Loktevskii) Mine, Upper Loktevka River, Rudnyi Altai, Altaiskii Krai, Western-Siberian Region, Russia

Year Discovered:

1839

View mineral photos:

Aurichalcite Mineral Photos and Locations

More Information

Mindat.org
Webmineral.com

Aurichalcite is a secondary mineral that forms in the oxidation zones of zinc and copper deposits. Crystals are typically acicular or fibrous and found in tufted aggregates but may also form as thick crusts; rarely columnar, laminated or granular. Aurichalcite's color is an attractive grass green to pale green. It is often associated with such colorful minerals as Azurite, Malachite, and Smithsonite. Aurichalcite can be confused with Rosasite. However, Rosasite is usually more massive but not lamellar and its Mohs hardness is 4.0 versus Aurichalcite's 1.0 - 2.0.

Distribution: Widespread in small amounts. Localities noteworthy for good specimens include: from the Loktevskii mine, upper Loktevka River, west Altai Mountains, Russia. At Monteponi, and in the Rosas mine, Sulcis, Sardinia, Italy. From Laurium, Greece. At Chessy, near Lyon, Rhône, France. In the USA, in Arizona, fine examples from Bisbee, Cochise County, in the Silver Hill mine, Pima County, and at the 79 mine, Gila County; from Cerro Gordo, Inyo County, California; at the Kelly and Graphic mines, Magdalena, Socorro County, New Mexico. In Utah, from the Tintic district, Juab County, at the Hidden Treasure mine, Tooele County, in the Apex mine, near St. George, Washington County, and from Big Cottonwood Canyon, Salt Lake County; at Leadville, Lake County, Colorado. In Mexico, rich specimens from the Ojuela mine, Mapimí, Durango, Mexico. At the Tchah Khuni mine, Anarak district, Iran. From Tsumeb, Namibia. At Kipushi, 28 km southwest of Lubumbashi, Katanga Province, Congo (Shaba Province, Zaire).

  
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