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. Agardite minerals are a member of the mixite structure group, which has the general chemical formula Cu2+6A(TO4)3(OH)6·3H2O, where A is a REE, Al, Ca, Pb, or Bi, and T is P or As. In addition to the four agardite minerals, the other members of the mixite mineral group are calciopetersite, goudeyite, mixite, petersite-(Ce), petersite-(Y), plumboagardite, and zálesíite. Agardite-(Y) from the Bou Skour mine in Djebel Sarhro, Morocco was the first of the agardite-group minerals to be characterized. It was described by Dietrich in 1969 and was named after Jules Agard, a French geologist at the Bureau de Recherches Géologiques et Minières, Orléans, France. Agardite-group minerals have subsequently been found in Germany, Czech Republic, Greece, Italy, Japan, Namibia, Poland, Spain, Switzerland, the United Kingdom, and the United States. See also List of minerals References Further reading Aufschluss 1977(5), 177–183. Steen, H. (2005): Ein Neufund von Agardit-(Y) aus Rotenbach im Feldberggebiet (südlicher Schwarzwald). Der Erzgräber 19, 70–72. Wittern: "Mineralfundorte in Deutschland", Schweizerbart (Stuttgart), 2001.*Wittern, A. (1995) Mineralien finden im Schwarzwald. Lapis 1985(11), 31–32. S. Weiss: "Mineralfundstellen, Deutschland West", Weise (Munich), 1990 Walenta, K. and Theye, T. (2004): Agardit-(Ce) von der Grube Clara im mittleren Schwarzwald. Aufschluss 55, 17–23. [with analysis of Johann material showing Nd > La]. Emser Hefte 15(3), 2–40 (1994). Heckmann, H. & Schertl, H.-P. (1990): Der Niederbergische Erzbergbau und seine Mineralien. Emser Hefte, 11 (2), 2–40. Pekov, I. V., Chukanov, N. V., Zadov, A. E., Voudouris, P., Magganas, A. and Katerinopoulos, A. (2010) Agardite-(Nd), IMA 2010-056. CNMNC Newsletter No. 7, February 2010, page 30; Mineralogical Magazine, 75, 27–31. Pekov, I. V., Chukanov, N. V., Zadov, A. E., Voudouris, P., Magganas, A., Katerinopoulos, A. (2011): Agardite-(Nd), NdCu6(AsO4)3(OH)6·3H2O from the Hilarion Mine, Lavrion, Greece: mineral description and chemical relations with other members of the agardite-zálesíite solid-solution system. Journal of Geosciences, 56, 249–255. Ambrino, P., Brizio, P., Ciriotti, M. E., Finello, G., Marello, B. (2009). Minerali della pietra di Luserna. AMI. CD-ROM. Piccoli, G. C., Maletto, G., Bosio,