Gjerdingenite-Mn from Norway - A new mineral species in the labuntsovite group: Descriptive data and crystal structure
- Autor(en)
- Gunnar Raade, N V Chukanov, Uwe Kolitsch, Steffen Möckel, Aleksandr E. Zadov, Igor V Pekov
- Abstrakt
Gjerdingenite-Mn occurs as orange-yellow to brownish prisms up to 1 mm long in miarolitic cavities of a sodic granite ('ekerite') at Gjerdingselva, Lunner, Oppland, Oslo Region, Norway. The simplified formula is (K,Na)2(Mn,Fe) [(Nb,Ti)4(Si 4O12)2(O,OH)4]ž 6H2O. It is the Mn-dominant analogue of gjerdingenite-Fe, the Ti analogue of kuzmenkoite-Mn and a dimorph of organovaite-Mn. The mineral is monoclinic, C2/m, with a = 14.563(3), b = 13.961(3), c = 7.851(2) A°, ß = 117.62(3)°, V = 1414.3(6) A° 3, Z = 2. The crystal structure was refined to R(F) = 0.079 on the basis of 1207 observed reflections and is compared to the structure of gjerdingenite-Fe. The strongest five reflections of the X-ray powder-diffraction pattern [dobs in A° (I) (hkl)] are: 6.96 (100) (020, 001), 4.94 (80) (021), 3.22 (90) (42-1, 400, 40-2 , 3.10 (80) (041, 022) and 2.510 (40) (44-1, 401, 40-3, 042). The mineral is optically biaxial (+) with a = 1.670(2), ß = 1.685(2), ? = 1.775(5); 2Vmeas = 52(8)°, 2Vcalc = 46(5)°. The axial dispersion is weak, r <v; the orientation is Z = a, Y = b. Mohs hardness is about 5; Dcalc = 2.93 g/cm 3. The pseudo-orthorhombic crystals are twinned on {001}, elongate along [010] and show the forms {001}, {100}, {201} and {021}. Some general aspects on the formation of labuntsovite-group minerals are discussed. Œ 2004 E. Schweizerbart'sche Verlagsbuchhandlung.
- Organisation(en)
- Institut für Mineralogie und Kristallographie
- Externe Organisation(en)
- University of Oslo (UiO), Russian Academy of Sciences, NPO Regenerator, Lomonosov Moscow State University (MSU)
- Journal
- European Journal of Mineralogy: an international journal of mineralogy, geochemistry and related sciences
- Band
- 16
- Seiten
- 979-987
- Anzahl der Seiten
- 9
- ISSN
- 0935-1221
- Publikationsdatum
- 2004
- Peer-reviewed
- Ja
- ÖFOS 2012
- 1051 Geologie, Mineralogie
- Link zum Portal
- https://ucris.univie.ac.at/portal/de/publications/gjerdingenitemn-from-norway--a-new-mineral-species-in-the-labuntsovite-group-descriptive-data-and-crystal-structure(0036bcd7-b17c-4d53-9084-52aff2cb970e).html