Aurichalcite is a hydrous copper-zinc carbonate forming delicate pale-blue to blue-green acicular crystal sprays. It is one of the most beautiful secondary Cu-Zn minerals and a classic of the Mexico-Arizona oxidation-zone collecting tradition.
Properties
- Formula: (Zn,Cu)5(CO3)2(OH)6
- Crystal system: Monoclinic
- Hardness: 1 – 2
- Color: Pale sky-blue to blue-green, turquoise
- Streak: Pale blue-green
- Luster: Silky to pearly
- Cleavage: Perfect on {010}
- Density: 3.6 – 4.2 g/cm³
Occurrence
Classic localities: Mina Ojuela (Mapimí, Mexico), 79 Mine and Bisbee (Arizona), Tsumeb (Namibia), Lavrion (Greece). Often associated with rosasite and hemimorphite on limonite.
Identification
Sky-blue acicular needle sprays + extreme softness + effervesces in dilute HCl + Cu-Zn carbonate chemistry. Distinguish from rosasite (similar habit but more solid blue-green plates) and chrysocolla (no needles, amorphous).
Collector Notes
79 Mine aurichalcite “fans” radiating on limonite are American classic specimens. Care: very fragile; dust easily damages the silky luster.
Found at these Localities
- Lavrion (Laurium) (拉夫里翁古铅锌银矿)
- Bisbee (Warren District) (比斯比铜矿)
- Mina Ojuela, Mapimí (马皮米奥胡埃拉矿)
- Tsumeb Mine (楚梅布矿)
