Redetermination of conichalcite, CaCu(AsO4)(OH)

Rachel R. Henderson, Hexiong Yang, Robert T. Downs, Robert A. Jenkins

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8 Scopus citations


The crystal structure of conichalcite [calcium copper(II) arsenate(V) hydroxide], with ideal formula CaCu(AsO4)(OH), was redetermined from a natural twinned specimen found in the Maria Catalina mine (Chile). In contrast to the previous refinement from photographic data [Qurashi & Barnes (1963). Can. Mineral. 7, 561-577], all atoms were refined with anisotropic displacement parameters and with the H atom located. Conichalcite belongs to the adelite mineral group. The Jahn-Teller-distorted [CuO6] octa-hedra share edges, forming chains running parallel to [010]. These chains are cross-linked by eight-coordinate Ca atoms and by sharing vertices with isolated AsO4 tetra-hedra. Of five calcium arsenate minerals in the adelite group, the [MO6] (M = Cu, Zn, Co, Ni and Mg) octa-hedron in conichalcite is the most distorted, and the donor-acceptor O - H⋯O distance is the shortest.

Original languageEnglish (US)
Pages (from-to)i53-i54
JournalActa Crystallographica Section E: Structure Reports Online
Issue number9
StatePublished - 2008

ASJC Scopus subject areas

  • General Chemistry
  • General Materials Science
  • Condensed Matter Physics


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