• journal_title：European Journal of Mineralogy
• Contributor：Gerald Giester ; Uwe Kolitsch ; Peter Leverett ; Peter Turner ; Peter A. Williams
• Publisher：E. Schweizerbart'sche Verlagsbuchhandlung Science Publishers
• Date：2007-
• Format：text/html
• Language：en
• Identifier：10.1127/0935-1221/2007/0019-0075
• journal_abbrev：Eur J Mineral
• issn：0935-1221
• volume：19
• issue：1
• firstpage：75
• section：Articles

d="p-1">The crystal structures of lavendulan from the Hilarion mine, Laurion, Greece, and isotypic sampleite from the Northparkes mine, New South Wales, Australia, have been determined from single-crystal diffraction data, resulting in a revision of the symmetry. The structure of lavendulan, NaCaCu₅(AsO₄)₄Cl · 5H₂O (space group P2₁/n, a = 10.011(1), b = 19.478(2), = 10.056(1) Å, β = 90.37(1)°, V = 1960.8(3) ų, Z = 4) was solved from X-ray data (MoK , CCD area detector) and refined to R1(F) = 5.35 % for 4179 observed reflections with F_o > 4σ (F_o). The structure of sampleite, NaCaCu₅(PO₄)₄Cl · 5H₂O, was determined from synchrotron data (CCD area detector) obtained from a twinned crystal (space group P2₁/n, a = 9.676(2), b = 19.284(4), c = 9.766(2) Å, β = 90.07(1)°, V = 1822.3(6) ų, Z = 4) and refined to R1(F) = 4.44 % for 2601 observed reflections with F_o > 4σ (F_o). The structure type is based on Cu(O,H₂O,Cl)₅ pyramids forming [Cu₄O₁₂Cl] clusters, which are connected by XO₄ (X = As,P) groups into heteropolyhedral sheets. These sheets ideally have p4mm symmetry and are aligned parallel to (010), i.e., the plane of the excellent cleavage, and are linked to adjacent parallel sheets via NaO₆ and CaO₇ polyhedra as well as by weak hydrogen bonding.

d="p-2">A polymorph of sampleite with the chemical formula NaCaCu₅(PO₄)₄Cl · nH₂O (n ~ 4.5) has been found at Lake Boga, Victoria, Australia. The crystal structure (space group P2₁/, a = 9.695(2), b = 9.673(2), c = 19.739(4) Å, β = 102.61(3)°, V = 1806.5(6) ų, Z = 4) was determined using single-crystal X-ray diffraction data (MoKα , CCD area detector) and refined to R1(F) = 14.67 % for 3189 observed reflections with F_o > 4σ (F_o). The heteropolyhedral sheet in the polymorph is topologically identical to that of sampleite (and lavendulan), but the stacking of these sheets is slightly different. Thus, the polymorph may be considered a polytype if the apparently slightly reduced water content of the polymorph is neglected. Some physicochemical properties of the sampleite polymorph are given.

d="p-3">Sheets identical to those in lavendulan are encountered in zdenekite, the Pb-analogue of lavendulan. Very similar sheets are found in andyrobertsite, calcio-andyrobertsite(−1M), calcio-andyrobertsite-2O, richelsdorfite, and probably bleasdaleite, mahnertite, lemanskiite and the inadequately characterized, lavendulan-related species shubnikovite.