Hostname: page-component-cd9895bd7-p9bg8 Total loading time: 0 Render date: 2024-12-26T18:58:17.153Z Has data issue: false hasContentIssue false
  • English
  • Français

Rickturnerite, Pb7O4[Mg(OH)4](OH)Cl3, a complex new lead oxychloride mineral

Published online by Cambridge University Press:  05 July 2018

M. S. Rumsey ,
S. V. Krivovichev ,
O. I. Siidra ,
C. A. Kirk ,
C. J. Stanley  and
J. Spratt
M. S. Rumsey*
Affiliation:
Mineralogy Department, Natural History Museum, Cromwell Road, London SW7 5BD, UK
S. V. Krivovichev
Affiliation:
Mineralogy Department, Natural History Museum, Cromwell Road, London SW7 5BD, UK
O. I. Siidra
Affiliation:
Mineralogy Department, Natural History Museum, Cromwell Road, London SW7 5BD, UK
C. A. Kirk
Affiliation:
Mineralogy Department, Natural History Museum, Cromwell Road, London SW7 5BD, UK
C. J. Stanley
Affiliation:
Mineralogy Department, Natural History Museum, Cromwell Road, London SW7 5BD, UK
J. Spratt
Affiliation:
Mineralogy Department, Natural History Museum, Cromwell Road, London SW7 5BD, UK
*
*E-mail: [email protected]
Get access Rights & Permissions [Opens in a new window]

Abstract

Rickturnerite, which has the ideal formula Pb7O4[Mg(OH)4](OH)Cl3, is a new mineral from Torr Works (Merehead) quarry, near the village of Cranmore in Somerset, United Kingdom. It occurs as pale emerald green to grey porous aggregates of disordered interwoven minute fibrous crystals with mereheadite, cerussite, calcite, aragonite, mimetite, hydrocerussite, “plumbonacrite” and an uncharacterized lead oxychloride, in cavities inside a manganite and pyrolusite pod. The crystals are typically less than 5 μm wide and 200 μm long, but they can reach 40 × 100 μm in cross-section and over 1 mm in length. The mineral is translucent with a vitreous lustre and each needle is brittle with an indistinct cleavage, breaking with a splintery fracture. The streak is white, the Mohs hardness ∼3 and the density calculated using the empirical formula 6.886 g cm–3. Electron microprobe analyses yielded PbO 87.7, MgO 1.79, CuO 0.14, Cl 6.62 wt.%; H2O was calculated on the basis of structural considerations as 2.27 wt.% totalling 97.02 wt.%. A charge-balanced formula, based on 12 anions, is Pb7.16Mg0.81Cu0.03Cl3.40H4.60O8.60. Rickturnerite is orthorhombic Pnma, with a = 5.8024(6), b = 22.717(2), c = 25.879(3) Å, V = 3411.2(6) Å3 and Z = 8. The diffraction pattern contains strong reflections that define a subcell with a = 5.8034(5), b = 11.3574(9), c = 12.939(2) Å, V = 852.9(6) Å3 (space group Pmm2 which is related to the real unit cell by the transformation matrix [100/020/002]), and weak reflections that correspond to doubled b and c parameters. Since the difference between the large and small cells is only in a number of split and low-occupancy positions in the disordered region of the structure we provide the description of the subcell structure. The five strongest lines in the X-ray powder diffraction pattern [listed as dobs (Å), Iobs, (hkl)] are as follows: 6.474, 100, (400); 3.233, 73, (107); 2.867, 57, (705); 5.636, 44, (011); 3.112, 31, (802). The crystal structure was solved by direct methods and refined using 1318 unique reflections to R1 = 0.063. The structure is composed of a fully ordered part consisting of double [O2Pb3]2+ chains of oxocentred [OPb4] tetrahedra extended along the b-axis, which together with Cl– ions form 2-dimensional blocks parallel to (001). In between these blocks, there is a disordered region containing ordered [Mg(OH)6]4– octahedra and low-occupancy Pb and OH sites with a slight degree of ordering; these produce the weak supercell reflections.

Keywords

rickturneritechloroxiphiteoxocentred tetrahedranew mineral specieslead magnesium oxychlorideMerehead quarrySomersetmineral nomenclatureTorr Works quarrynew structure type
Type
Research Article
Information
Mineralogical Magazine , Volume 76 , Issue 1 , February 2012 , pp. 59 - 73
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 2012

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Alabaster, C. (1989) The Wesley mine: a further occurrence of manganese oxide-hosted lead oxychloride minerals in the Bristol district. Journal of the Russell Society, 2, 29–47.Google Scholar
Anthony, J.W., Bideaux, R.A., Bladh, K.W. and Nichols, M.C. (2001) Handbook of Mineralogy (5 volumes and online at http://www.handbookofmineralogy.org.) Mineralogical Society of America, Chantilly, Virginia, USA and Mineral Data Publishing, Tucson, Arizona, USA.Google Scholar
Criddle, A.J. (1998) Ore microscopy and Photometry. Pp. 1–74. in: Modern Approaches to Ore and Environmental Mineralogy (Cabri, L.J. and Vaughan, D.J., editors). Mineralogical Association of Canada Short Course Series, 27. Mineralogical Association of Canada, Quebec, Canada.Google Scholar
Din, V.K., Symes, R.F. and Williams, C.T. (1986) Lithogeochemical study of some Mendip county rocks with particular reference to boron. Bulletin of the British Museum (Natural History), Geological Series Miscellania II, 40, 247–258.Google Scholar
Green, G.W. (1958) The central Mendip lead-zinc orefield. Bulletin of the Geological Survey of Great Britain, 14, 70–90.Google Scholar
Krivovichev, S.V. and Burns, P.C. (2001a) Crystal chemistry of lead oxide chlorides. I. Crystal structures of synthetic mendipite, Pb3O2Cl2, and synthetic damaraite, Pb3O2(OH)Cl. European Journal of Mineralogy, 13, 801–809.CrossRefGoogle Scholar
Krivovichev, S.V. and Burns, P.C. (2001b) Crystal chemistry of lead oxide chlorides. II. Crystal structure of Pb7O4(OH)4Cl2. European Journal of Mineralogy 14, 135–139.CrossRefGoogle Scholar
Krivovichev, S.V., Avdontseva, E. Yu. and Burns, P.C. (2004) Synthesis and crystal structure of Pb3O2(SeO3). Zeitschrift für Anorganische und Allgemeine Chemie, 630, 558–562.CrossRefGoogle Scholar
Krivovichev, S.V., Turner, R., Rumsey, M.S., Siidra, O.I. and Kirk, C.A. (2009) The crystal structure and chemistry of mereheadite. Mineralogical Magazine, 73, 103–117.CrossRefGoogle Scholar
Pouchou, J.L. and Pichoir, F. (1985) ‘PAP’ j(rZ) procedure for improved quantitative microanalysis. Pp. 104–106. in: Microbeam Analysis (Armstrong, J.T., editor). San Francisco Press, San Francisco, California, USA.Google Scholar
Sheldrick, G.M. (2008) A short history of SHELX. Acta Crystallographica, A64, 112–122.CrossRefGoogle Scholar
Siidra, O.I., Krivovichev, S.V. and Depmeier, W. (2007) Structure and mechanism of the ionic conductivity of the nonstoichiometric compound Pb2+xOCl2+2x. Doklady Physical Chemistry, 414, 128–131.CrossRefGoogle Scholar
Siidra, O.I., Krivovichev, S.V., Armbruster, T. and Depmeier, W. (2008a) Crystal chemistry of the mendipite-type system Pb3O2Cl2-Pb3O2Br2. Zeitschrift für Kristallographie, 223, 204–211.CrossRefGoogle Scholar
Siidra, O.I., Krivovichev, S.V., Turner, R. and Rumsey, M.S. (2008b) Chloroxiphite Pb3CuO2(OH)2Cl2: structure refinement and description in terms of oxocentred OPb4 tetrahedra. Mineralogical Magazine, 72, 793–798.CrossRefGoogle Scholar
Siidra, O.I., Krivovichev, S.V. and Filatov, S.K. (2008c) Minerals and synthetic Pb(II) compounds with oxocentered tetrahedra: review and classification. Zeitschrift für Kristallographie, 223, 114–126.CrossRefGoogle Scholar
Siidra, O.I., Krivovichev, S.V. and Depmeier, W. (2008d) Crystal chemistry of natural and synthetic lead oxohalides: II. Crystal structure of Pb7O4(OH)4Br2. Geology of Ore Deposits, 50, 801–805.CrossRefGoogle Scholar
Spencer, L.J. (1923) New lead-copper minerals from the Mendip Hills (Somerset). Mineralogical Magazine, 20, 67–92.CrossRefGoogle Scholar
Stoe and Cie (2007) X-area, version 1.42: Program for Acquisition and Analysis of Data. Stoe and Cie GmbH, Darmstadt, Germany. Symes, R.F. and Embrey, P.G. (1977) Mendipite and other rare oxychloride minerals from the Mendip Hills, Somerset, England. The Mineralogical Record, 8, 298–303.Google Scholar
Symes, R.F., Cressey, G., Criddle, A.J., Stanley, C.J., Francis, J.G. and G.C., Jones (1994) Parkinsonite, (Pb,Mo,)8O8Cl2, a new mineral from Merehead Quarry, Somerset. Mineralogical Magazine, 58, 59–68.CrossRefGoogle Scholar
Turner, R. (2006) A mechanism for the formation of the mineralized Mn deposits at Merehead Quarry, Cranmore, Somerset, England. Mineralogical Magazine, 70, 629–655.CrossRefGoogle Scholar
Turner, R. and Rumsey, M.S. (2010) The minerals of the Mendip Hills and their relationships. Journal of the Russell Society, 13, 3–46.Google Scholar
M.D., Welch, M.A., Cooper, Hawthorne, F.C. and A.J., Criddle (2000) Symesite, Pb10(SO4)O7Cl4(H2O), a new PbO-related mineral: description and crystal structure. American Mineralogist, 85, 1526–1533.Google Scholar
Welch, M.D., Criddle, A.J. and Symes, R.F. (1998) Mereheadite Pb2O(OH)Cl: a new litharge-related oxychloride from Merehead Quarry, Cranmore, Somerset. Mineralogical Magazine, 62, 387–393.CrossRefGoogle Scholar
Supplementary material: File

Rumsey et al. supplementary material

Cif file

Download Rumsey et al. supplementary material(File)
File 65.1 KB