Niedermayrite, Cu₄Cd(SO₄)₂(OH)₆·4H₂O, a new mineral from the Lavrion District, Greece

Autor(en)

Gerald Giester, Branko Rieck, Franz Brandstätter

Abstrakt

iedermayrite, Cu4Cd(SO4)2(OH)6.4H2O, is a new mineral discovered in 1995 in the Km3-area of the Lavrion mining district, Greece. It forms tiny euhedral plates, commonly intergrown as green crusts up to several cm2 in size on a matrix consisting of a brecciated marble with sphalerite, chalcopyrite, galena, greenockite, hawleyite, and pyrite. Assocd. secondary minerals are gypsum, malachite, chalcanthite, brochantite, hemimorphite, hydrozincite, aurichalcite, one unknown Cd-sulfate, monteponite, and otavite. Niedermayrite is non-fluorescent and has a bluish-green color with vitreous luster, the streak is white. The crystals are brittle with perfect cleavage parallel {010}. Optics: biaxial (-) with nalpha(calc.), nbeta, and ngamma = 1.609, 1.642(2), and 1.661(2), resp.; orientation nalpha//b. The calcd. d. is 3.292 gcm-3. The most prominent form is {010}. Anal. by electron microprobe gives CdO 16.5, CuO 45.7, SO3 21.6, H2O 16.2 wt.% (calc. to 100% sum) and the empirical formula Cu4.29Cd0.96S2.01O11.28.6.71 H2O (based on 18 O p.f.u.). By TGA an H2O content of 18.9 wt.% was obtained. The ideal formula (confirmed by the crystal structure refinement) is Cu4Cd(SO4)2(OH)6.4H2O with a theor. H2O content of 17.2 wt.%. The strongest lines in the x-ray powder diffraction pattern (Gandolfi camera, visually estd. I, refined lattice parameters a = 5.535(2), b = 21.947(9), c = 6.085(2) .ANG., beta = 91.98(3)°) are presented. The mineral is monoclinic, P21/m, Z = 2, a = 5.543(1) .ANG., b = 21.995(4) .ANG., c =6.079(1) .ANG., beta = 92.04(3)°, V = 740.7(2) .ANG.3. The crystal structure was detd. by single crystal x-ray methods and was refined to R1 =0.026, wR2 = 0.056. The structure of niedermayrite is characterized by 2¥ [Cu4(OH)6O2]2- sheets of edge-sharing Cu coordination octahedra parallel to (010) with attached SO4 tetrahedra, and intercalated CdO2(H2O)4 octahedra with a system of hydrogen bonds. Close relationships to the crystal structures of christelite and campigliaite exist. The new mineral is named for Dr. Gerhard Niedermayr, Naturhistorisches Museum Wien, Austria.

Organisation(en)

Institut für Mineralogie und Kristallographie

Externe Organisation(en)

Naturhistorisches Museum Wien (NHM)

Journal

Mineralogy and Petrology

Band

63

Seiten

19-34

Anzahl der Seiten

16

ISSN

0930-0708

Publikationsdatum

1998

Peer-reviewed

Ja

ÖFOS 2012

105116 Mineralogie, 105113 Kristallographie

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/niedermayrite-cu4cdso42oh64h2o-a-new-mineral-from-the-lavrion-district-greece(8cf80f35-049d-41e5-bd3a-385e227ff792).html