Agardite

Agardite-(Y), Agardite-(Ce), Agardite-(Nd), Agardite-(La)

An example of Agardite-(Ce) in the form of pistachio-green acicular crystals on contrasting matrix
General
Category Arsenate minerals
Formula
(repeating unit)		 (REE,Ca)Cu6(AsO4)3(OH)6·3H2O
Strunz classification 08.DL.15
Dana classification (Y): 42.05.01.02, (Ce): 42.05.01.02e, (Nd): 42.05.01.02b, (La): 42.05.01.02a
Crystal symmetry Hexagonal – dipyramidal, H-M symbol (6/m), space group P63/m
Unit cell a = 13.59 Å, c = 5.89 Å, Z = 2
Identification
Color Yellow green
Crystal habit Acicular
Cleavage None
Fracture Conchoidal
Mohs scale hardness 3–4
Luster Vitreous
Streak Greenish white
Specific gravity 3.7 (measured), 3.775 (calculated)
Refractive index nω = 1.725, nε = 1.81
Birefringence 0.085
Pleochroism yellowish green
References [1][2]

Agardite is a mineral group consisting of agardite-(Y),[3][4] agardite-(Ce),[5] agardite-(Nd),[6] and agardite-(La).[7] 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,[8] goudeyite,[9] mixite,[10] petersite-(Ce),[11] petersite-(Y),[12][13] plumboagardite,[14] and zálesíite.[15]

Agardite-(Y) from the Bou Skour mine in Djebel Sarhro, Morocco was the first of the agardite-group minerals to be characterized.[16] 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.[17] Agardite-group minerals have subsequently been found in Germany,[18] Czech Republic,[19] Greece,[20] Italy,[21] Japan,[22] Namibia,[23] Poland,[24] Spain,[25] Switzerland,[26] the United Kingdom,[27] and the United States.[28]

References

Wikimedia Commons has media related to Agardite-(Ce).
  1. ↑ Agardite. Mindat.org
  2. ↑ Agardite. Webmineral
  3. ↑ Dietrich J E, Orliac M, Permingeat F (1969) L’agardite, une nouvelle espèce minérale, et le problème du chlorotile, Bulletin de la Société Française de Minéralogie et de Cristallographie 92, 420-434
  4. ↑ Nickel E H, Mandarino J A (1987) Procedures involving the IMA Commission on New Minerals and Mineral Names and guidelines on mineral nomenclature, American Mineralogist 72, 1031-1042
  5. ↑ Walenta K, Theye T (2004) Agardite-(Ce) of the Clara mine in the central Black Forest, Aufschluss 55, 17–23
  6. ↑ 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 57, 249-255
  7. ↑ Fehr T, Hochleitner R (1984) Agardite-La. Ein neues mineral von Lavrion, Griechenland, Lapis 9, 22-37
  8. ↑ Sejkora J, Novotný P, Novák M, Šrein V, Berlepsch P (2005) Calciopetersite from Domašov nad Bystricí, Northern Moravia, Czech Republic, a new mineral species of the mixite group, The Canadian Mineralogist 43, 1393-1400
  9. ↑ Wise W S (1978) Parnauite and goudeyite, two new copper arsenate minerals from the Majuba Hill Mine, Pershing County, Nevada, American Mineralogist 63, 704-708
  10. ↑ Schrauf A (1880) Ueber Arsenate von Joachimsthal. 1. Mixit, ein neues Kupferwismuthhydroarsenat, Zeitschrift für Krystallographie und Mineralogie 4, 277-285
  11. ↑ Williams P A, Hatert F, Pasero M, Mills S J (2014) IMA Commission on new minerals, nomenclature and classification (CNMNC) Newsletter 20. New minerals and nomenclature modifications approved in 2014. Mineralogical Magazine 78, 549-558
  12. ↑ Peacor D R, Dunn P J (1982) Petersite, a REE and phosphate analog of mixite, American Mineralogist 67, 1039-1042
  13. ↑ Nickel E H, Mandarino J A (1987) Procedures involving the IMA Commission on New Minerals and Mineral Names and guidelines on mineral nomenclature, American Mineralogist 72, 1031-1042
  14. ↑ Walenta K, Theye T (2005) Plumboagardite, a new mineral of the mixite group from an occurrence in the Southern Black Forest, Neues Jahrbuch für Mineralogie, Abhandlungen 181, 219-224
  15. ↑ Sejkora J, Rídkošil T, Šrein V (1999) Zálesíite, a new mineral of the mixite group, from Zálesí, Rychlebské hory Mts., Czech Republic, Neues Jahrbuch für Mineralogie, Abhandlungen 175, 105-124.
  16. ↑ Dietrich J E, Orliac M, Permingeat F (1969) L’agardite, une nouvelle espèce minérale, et le problème du chlorotile, Bulletin de la Société Française de Minéralogie et de Cristallographie, 92, 420-434
  17. ↑ Anthony J W, Bideaux R A, Bladh K W, and Nichols M C (1990) Handbook of Mineralogy, Mineral Data Publishing, Tucson Arizona, USA, by permission of the Mineralogical Society of America.
  18. ↑ K. Walenta: "Die Mineralien des Schwarzwaldes", Weise (Munich), 1992.
  19. ↑ Sejkora J., Pauliš P., Kopista J.: Agardit-(Y) z ložiska Sn-W Cínovec v Krušných horách (Česká republika). Bulletin mineralogicko-petrografického oddělení Národního muzea v Praze, 2011, 19, 1, 64-68.
  20. ↑ LAPIS 24 (7/8) 1999; Wendel, W. and Markl, G. (1999) Lavrion: Mineralogische Klassiker und Raritäten für Sammler. LAPIS 24 (7/8):34-52.
  21. ↑ Palenzona, A., Armellino, G., Bulgarelli, G. (1994): Le agarditi della Liguria. Rivista Mineralogica Italiana, 4/1994, 354-356.
  22. ↑ Anthony, Bideaux, Bladh, Nichols: "Handbook of Mineralogy", Vol. 4, 2000.
  23. ↑ Gebhard, G. (1999): Tsumeb II. A Unique Mineral Locality. GG Publishing, Grossenseifen, Germany.
  24. ↑ SiudaR., K. Gal-Solymos, Kruszewski L., 2006: Agardite-(La)-duftite and scorodite-köttigite-like mineral paragenesis from supergenic zone of the Miedzianka deposit (Rudawy Janowickie Mts., Poland) – preliminary report. Mineralogia Polonica Special Papers, 29, 192-195.
  25. ↑ Anthony, Bideaux, Bladh, Nichols: "Handbook of Mineralogy", Vol. 4, 2000.
  26. ↑ Stalder, H. A., Wagner, A., Graeser, S. and Stuker, P. (1998): "Mineralienlexikon der Schweiz", Verlag Wepf & Co. (Basel), p. 24.
  27. ↑ Goley, P. and Williams R. (1995) Cornish Mineral Reference Manual. Endsleigh Publications
  28. ↑ Pemberton, H. Earl (1983), Minerals of California; Van Nostrand Reinholt Press: 323.


Further Reading