Agardite-(Ce) Locality: Tsumeb Mine (Tsumcorp Mine), Tsumeb , Otjikoto (Oshikoto) Region, Namibia ( Locality at mindat.org ) Size: 2.6 x 1.6 x 0.6 cm. A rich example of Agardite-(Ce) in the form of pistachio-green acicular crystals on contrasting matrix. Ex. Willy Israel Collection. — Photo: Robert M. Lavinsky · CC BY-SA 3.0
Agardite-(Ce)
Agardite is a mineral group consisting of agardite-(Y), agardite-(Ce), agardite-(Nd), and agardite-(La). They comprise a group of minerals that are hydrous hydrated arsenates of rare-earth elements (REE) and copper, with the general chemical formula (REE,Ca)Cu6(AsO4)3(OH)6·3H2O. Yttrium, cerium, neodymium, lanthanum, as well as trace to minor amounts of other REEs, are present in their structure. Agardite-(Y) is probably the most often found representative. They form needle-like yellow-green (variably hued) crystals in the hexagonal crystal system.
Intro adapted from Wikipedia (CC BY-SA).
Agardite-(Ce) is an IMA-recognized mineral species in the arsenate class, with the chemical formula CeCu²⁺₆(AsO₄)₃(OH)₆·3H₂O.
It crystallizes in the hexagonal crystal system (space group P6_3/m). It is a member of the Mixite structural group.
Key properties: Mohs hardness 3; specific gravity 3.7; Greenish to pale yellow streak; Vitreous to silky luster; optically uniaxial.
IMA symbol Agr-Ce, IMA status: approved, named in 2003.
Found in the oxidation zone of polymetallic sulfide deposits.
It is found associated with Barite, quartz, goethite, cornwallite (Clara mine).
By analogy to agardite-(Y), with a suffix for its rare-earth content dominated by Cerium.