 |
Chemical Formula | (Zn,Cu)5(CO3)2(OH)6 | |||||
|
Composition | A basic carbonate of zinc and copper. (The ratio of zinc to copper is about 5:2) | |||||
|
Color | Light blue, sky blue, blue-green, pale green | |||||
|
Streak | Pale blue-green to white | |||||
|
Hardness | 2 (Due to crystal habits cannot be determined by practical methods) | |||||
|
Crystal Forms and Aggregates |
(Orthorhombic) Usually occurs as a mat of tiny, thin, interwoven needles. Also occurs plumose, as crusts, as thin scales, radiating, and as tiny balls of radiating crystals. Individual crystals, which can rarely be seen with the naked eye, are usually elongated, and occasionally tabular. | |||||
|
Transparency | Translucent | |||||
|
Specific Gravity | 3.6 - 4.2 | |||||
|
Luster | Silky to pearly | |||||
|
Cleavage | Indiscernible | |||||
|
Fracture | Uneven | |||||
|
Tenacity | Slightly flexible and sectile | |||||
|
Other Names |  Brass Ore |
|||||
|
In Group | Carbonates | |||||
|
All About | Most Aurichalcite specimens are composed of tiny needles which may rub off and leave a blue residue of tiny crystals on a surface. Specimens should be handled as little as possible and washing them with water is not recommended. | |||||
|
Uses | Aurichalcite is considered a natural brass ore, since it is composed of zinc and copper, the constituents of brass. However, it occurs much too sparingly, and there are no practical methods for brass to be extracted from it. It is, though, an ore of zinc when found in mines where there exists workable deposits of zinc. Good specimens of Aurichalcite are popular among mineral collectors. | |||||
|
Striking Features | Color, crystal habits, fragility, and occurrences | |||||
|
Complex Tests | Effervesces in dilute hydrochloric acid | |||||
|
Popularity (1-4 | 3 | |||||
|
Prevalence (1-3) | 3 | |||||
|
Demand (1-3) | 2 | |||||
|
Distinguishing Similar Minerals |
Aurichalcite's distinctive properties and occurrences distinguish it from basically every mineral, but Cuproadamite may resemble it in looks but varies in physical properties. | |||||
|
Commonly Occurs With |
Hemimorphite, Adamite, Limonite, Smithsonite, Austinite, Calcite, Azurite, Malachite | |||||
|
Noteworthy Localities |
Aurichalcite has been found in Tsumeb, Namibia; Chessy, France; Laurium, Greece; the Leadhills of Scotland; in England in Matlock, Derbyshire and Caldbeck Fells (Cumbria); and in Altai, Siberia, Russia. The best specimens currently come from Mapimi, Durango, Mexico, associated with Hemimorphite and Adamite on a brown Limonite matrix. In the U.S. it comes from Arizona in the No. 79 Mine in Hayden, Gila Co., from the Copper Queen Mine in Bisbee, Cochise Co., and from the Silver Hill Mine in Pima Co. Other localities include Magdalena, Soccoro Co., New Mexico; Stockton, Tooele Co. and Cotton Canyon, Salt Lake Co., Utah; the Grand Deposit Mine of White Pine Co., Nevada; the Darwin District of Inyo Co., California; and the Tin Mountain Mine, Custer Co., South Dakota. Small amounts have also been reported at the Sterling Hill Mine in Ogdensburg, Sussex Co., New Jersey. | |||||
|
Picture Icon Links |
|
|||||
|
Picture Links | 1. Pale
acicular Aurichalcite crystals 2. Radiating spray of Aurichalcite crystals |
