Hostname: page-component-586b7cd67f-rcrh6 Total loading time: 0 Render date: 2024-11-27T15:49:26.005Z Has data issue: false hasContentIssue false
  • English
  • Français

Parkinsonite, (Pb,Mo, □)8O8Cl2, a new mineral from Merehead Quarry, Somerset

Published online by Cambridge University Press:  05 July 2018

R. F. Symes ,
G. Cressey ,
A. J. Griddle ,
C. J. Stanley ,
J. G. Francis  and
G. C. Jones
R. F. Symes
Affiliation:
Department of Mineralogy, Natural History Museum, Cromwell Road, London SW7 5BD, UK
G. Cressey
Affiliation:
Department of Mineralogy, Natural History Museum, Cromwell Road, London SW7 5BD, UK
A. J. Griddle
Affiliation:
Department of Mineralogy, Natural History Museum, Cromwell Road, London SW7 5BD, UK
C. J. Stanley
Affiliation:
Department of Mineralogy, Natural History Museum, Cromwell Road, London SW7 5BD, UK
J. G. Francis
Affiliation:
Department of Mineralogy, Natural History Museum, Cromwell Road, London SW7 5BD, UK
G. C. Jones
Affiliation:
Department of Mineralogy, Natural History Museum, Cromwell Road, London SW7 5BD, UK
Get access Rights & Permissions [Opens in a new window]

Abstract

Parkinsonite, ideally (Pb,Mo,□)8O8Cl2, is a new mineral from the Merehead Quarry, Cranmore, Somerset, England. It occurs as compact clusters or patches of red to purplish red bladed crystals, which have an adamantine lustre and a perfect {001} cleavage and occupy fractures and cavities in carbonate vughs in veins of manganese and iron oxide and hydroxide minerals. Associated minerals are mendipite, diaboleite, chloroxiphite, wulfenite, cerussite and hydrocerussite. Discrete crystals were not found; intergrown crystalline aggregates are the usual form of occurrence. The maximum grain size is about 300 × 100 µm, but most grains are appreciably smaller. Parkinsonite was synthesized using high purity chemicals. The measured density of the synthetic material is 7.32 g/cm3; the calculated density is 7.39 g/cm3, the difference being due to minor impurity and slight porosity in the synthetic sample. Parkinsonite is translucent. Reflectance spectra were obtained in air and in oil. Refractive indices calculated from these (at 589 nm) are for Ro, 2.58, and Re', 2.42, i.e. uniaxial negative. VHN50 is 113–133 from which the calculated Mobs hardness is 2–2.5.

X-ray studies show that parkinsonite is tetragonal with space group I4/mmm, I4̄2m, I4̄m2, I4/mm, or I422 and a 3.9922(3), c 22.514(2) Å. It has a cell volume of 358.82(5) Å3 with Z = 1. The strongest six lines of the X-ray powder diffraction pattern are [d in Å (I) (hkl)] 2.823, 2.813(100) (110,008); 5.63(85) (004); 2.251(33) (116, 0.0.10); 2.988(27) (105); 3.750(15) (006); 1.994(11) (200,118). Averaged electron microprobe analyses give the empirical formula Pb6.34Mo0.89□0.77O8.02Cl1.98 on the basis of 10 atoms [O + Cl]. The name is for Reginald F. D. Parkinson, mineral collector of Somerset, UK, who first found the mineral.

Keywords

parkinsonitenew minerallead molybdenum oxychlorideMerehead Quarry
Type
Mineralogy
Information
Mineralogical Magazine , Volume 58 , Issue 390 , March 1994 , pp. 59 - 68
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1994

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. J. Russell Soc, 2, 29–6.Google Scholar
Aurivillius, B. (1982) On the crystal structure of a number of non-stoichiometric mixed lead oxide halides composed of PbO-like blocks and single halogen layers. Chemica Scripta, 19, 97–107.Google Scholar
Criddle, A. J., Stanley, C. J., Chisholm, J. E., and Fejer, E. E. (1983) Henryite, a new copper-silver telluride from Bisbee, Arizona. Bull. Mineral., 106, 511–17.Google Scholar
Din, V. K., Symes, R. F. and Williams, C. T. (1986) Lithogeochemical study of some Mendip country rocks with particular reference to boron. Bull. British Museum (Natural History), Geol. Ser., 40, 247–58.Google Scholar
Humphreys, D. A., Thomas, J. H. Williams, P. A., and Symes, R. F. (1980) The chemical stability of mendipite, diaboleite, chloroxiphite and cumen-geite and their relationship to other secondary Pb(II) minerals. Mineral. Mag., 43, 901–4.CrossRefGoogle Scholar
Ridgway, R. (1912) Colour standards and colour nomenclature. Published Robert Ridgway, Baltimore. 43 pp, 53 plates.CrossRefGoogle Scholar
Spencer, L. J. and Mountain, E. O. (1923) New lead-copper minerals from the Mendip Hills. Mineral. Mag., 20, 67–92.Google Scholar
Stanley, C. J., Jones, G. C, Hart, A. D., Keller, P., and Lloyd D. (1991) Barstowite, 3PbCl2PbCO3-H2O, a new mineral from Bounds Cliff, St Endellion, Cornwall. Mineral. Mag., 55, 121–5.CrossRefGoogle Scholar
Symes, R. F. and Embrey, P. G. (1977) Mendipite and other rare oxychloride minerals from the Mendip Hills, Somerset, England. Mineral. Record, 8, 298–303.Google Scholar