Structural and compositional variations of basic Cu(II) chlorides in the herbertsmithite and gillardite structure field. (2nd January 2018)

• Record Type: Journal Article
• Authors: Sciberras, Matthew J.; Leverett, Peter; Williams, Peter A.; Schlüter, Jochen; Malcherek, Thomas; Welch, Mark D.; Downes, Peter J.; Hibbs, David E.; Kampf, Anthony R.
• Is Part Of: Mineralogical magazine. Volume 81:Number 1(2017)
• Page Start: 123
• Page End: 134
• Publication Date: 2018-01-02
• Subjects: paratacamite, -- paratacamite-(Mg), -- paratacamite-(Ni), -- herbertsmithite, -- gillardite, -- compositional, -- boundary, -- crystal structure; Mineralogy -- Periodicals; Mineralogy -- Great Britain -- Periodicals; 549.05
• DOI: 10.1180/minmag.2016.080.079
• Languages: English
• ISSNs: 0026-461X

Abstract

Abstract: Natural samples of the substituted basic Cu(II) chloride series, Cu4–x M x 2+ (OH)6 Cl2 ( M = Zn, Ni, or Mg) were investigated by single-crystal X-ray diffraction in order to elucidate compositional boundaries associated with paratacamite and its congeners. The compositional ranges examined are Cu3.65 Zn0.35 (OH)6 Cl2 – Cu3.36 Zn0.64 (OH)6 Cl2 and Cu3.61 Ni0.39 (OH)6 Cl2 – Cu3.13 Ni0.87 (OH)6 Cl2, along with a single Mg-bearing phase. The majority of samples studied have trigonal symmetry ( R 3̄ m ) analogous to that of herbertsmithite (Zn) and gillardite (Ni), with a ≈ 6.8, c ≈ 14.0 Å. Crystallographic variations for these samples caused by composition are compared with both published and new data for the R 3̄ m sub-cell of paratacamite, paratacamite-(Mg) and paratacamite-(Ni). The observed trends suggest that the composition of end-members associated with the paratacamite congeners depend upon the nature of the substituting cation.