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Mereheadite

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Torr Works Quarry General View, July 2005

Torr Works Quarry, Cranmore, Somerset, England, UK
Formula:
Pb47Cl25(OH)13O24(CO3)(BO3)2
Formula originally assumed to be Pb2O(OH)Cl.
Colour:
pale yellow to reddish-orange
Lustre:
Vitreous, Resinous
Hardness:
Specific Gravity:
7.12
Crystal System:
Monoclinic
Name:
Named after Merehead quarry, Somerset, source of this and other unusual lead secondary minerals.
Related to symesite.


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Classification of MereheaditeHide

Approved
First Published:
1998
3.DC.45

3 : HALIDES
D : Oxyhalides, hydroxyhalides and related double halides
C : With Pb (As,Sb,Bi), without Cu

Physical Properties of MereheaditeHide

Vitreous, Resinous
Transparency:
Transparent, Translucent
Colour:
pale yellow to reddish-orange
Streak:
White
Hardness:
3½ on Mohs scale
Tenacity:
Brittle
Cleavage:
Perfect
(001)
Fracture:
Hackly, Conchoidal
Density:
7.12 g/cm3 (Measured)    7.31 g/cm3 (Calculated)

Optical Data of MereheaditeHide

Type:
Biaxial
RI values:
nα = 2.190 nγ = 2.280
Max Birefringence:
δ = 0.090
Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.
Surface Relief:
Moderate
Dispersion:
relatively strong
Pleochroism:
Non-pleochroic

Chemical Properties of MereheaditeHide

Formula:
Pb47Cl25(OH)13O24(CO3)(BO3)2

Formula originally assumed to be Pb2O(OH)Cl.
IMA Formula:
Pb47O24(OH)13Cl25(BO3)2(CO3)

Crystallography of MereheaditeHide

Crystal System:
Monoclinic
Class (H-M):
m - Domatic
Cell Parameters:
a = 17.372(1) Å, b = 27.9419(19) Å, c = 10.6661(6) Å
β = 93.152(5)°
Ratio:
a:b:c = 0.622 : 1 : 0.382
Unit Cell V:
5169.6 ų
Comment:
SG Cm; originally reported cell (Welch et al., 1998): C2/c, 5.680, 5.565, 13.143 A, 90.64°.

Type Occurrence of MereheaditeHide

General Appearance of Type Material:
Compact masses
Place of Conservation of Type Material:
Natural History Museum, London, England, specimen BM 1965,285 and
polished mount E.1175.

Synonyms of MereheaditeHide

Other Language Names for MereheaditeHide

German:Mereheadit
Spanish:Mereheadita

Common AssociatesHide

Associated Minerals Based on Photo Data:
Mendipite15 photos of Mereheadite associated with Mendipite on mindat.org.
Chloroxiphite10 photos of Mereheadite associated with Chloroxiphite on mindat.org.
Rickturnerite9 photos of Mereheadite associated with Rickturnerite on mindat.org.
Crednerite7 photos of Mereheadite associated with Crednerite on mindat.org.
Plumbonacrite3 photos of Mereheadite associated with Plumbonacrite on mindat.org.
Parkinsonite3 photos of Mereheadite associated with Parkinsonite on mindat.org.
Diaboleite3 photos of Mereheadite associated with Diaboleite on mindat.org.
Hydrocerussite2 photos of Mereheadite associated with Hydrocerussite on mindat.org.
Symesite2 photos of Mereheadite associated with Symesite on mindat.org.
Calcite1 photo of Mereheadite associated with Calcite on mindat.org.

Related Minerals - Nickel-Strunz GroupingHide

3.DC.05LaurionitePbCl(OH)Orth. mmm (2/m 2/m 2/m)
3.DC.05ParalaurionitePbCl(OH)Mon. 2/m : B2/m
3.DC.10FiedleritePb3FCl4(OH) · H2OMon. 2/m
3.DC.15PenfielditePb2Cl3(OH)Hex. 6 : P6
3.DC.20LaurelitePb7F12Cl2Hex. 6 : P6
3.DC.25Bismoclite(BiO)ClTet. 4/mmm (4/m 2/m 2/m) : P4/nmm
3.DC.25Daubréeite(BiO)(OH,Cl)Tet. 4/mmm (4/m 2/m 2/m) : P4/nmm
3.DC.25MatlockitePbFClTet. 4/mmm (4/m 2/m 2/m) : P4/nmm
3.DC.25RorisiteCaFClTet.
3.DC.25Zavaritskite(BiO)FTet.
3.DC.25ZhangpeishaniteBaFClTet. 4/mmm (4/m 2/m 2/m) : P4/nmm
3.DC.30NadoritePbSbClO2Orth. mmm (2/m 2/m 2/m) : Cmcm
3.DC.30PeritePbBiClO2Orth. mmm (2/m 2/m 2/m) : Cmcm
3.DC.35AravaipaitePb3AlF9 · H2OTric.
3.DC.37CalcioaravaipaitePbCa2AlF9Tric. 1
3.DC.40ThorikositePb3Cl2(OH)(SbO3,AsO3)Tet. 4/mmm (4/m 2/m 2/m) : I4/mmm
3.DC.50BlixitePb2(O,OH)2ClOrth.
3.DC.55PinalitePb3WO5Cl2Orth.
3.DC.60SymesitePb10(SO4)O7Cl4 · H2OTric. 1 : P1
3.DC.65EcdemitePb6Cl4(As2O7)Tet.
3.DC.65HeliophyllitePb6Cl4(As2O7)Orth.
3.DC.70MendipitePb3Cl2O2Orth. 2 2 2 : P21 21 21
3.DC.75DamaraitePb3Cl(OH)O2Orth. mm2 : Pmc21
3.DC.80OnoratoiteSb8Cl2O11Tric. 1 : P1
3.DC.85CotunnitePbCl2Orth. mmm (2/m 2/m 2/m)
3.DC.90PseudocotunniteK2PbCl4Orth.
3.DC.95BarstowitePb4Cl6(CO3) · H2OMon. 2/m : P21/m

Other InformationHide

Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

References for MereheaditeHide

Reference List:
Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
Welch, M.D., Criddle, A.J., Symes, R.F. (1998) Mereheadite, Pb2O(OH)Cl: a new litharge-related oxychloride from Merehead Quarry, Cranmore, Somerset. Mineralogical Magazine: 62: 387-393.
Jambor, J.L., Pertsev, N.N., Roberts, A.C. (1999) New mineral names. American Mineralogist: 84: 1195-1198.
Krivovichev, S.V., Turner, R., Rumsey, M., Siidra, O.I., Kirk. C.A. (2009) The crystal structure and chemistry of mereheadite. Mineralogical Magazine: 73: 103-117.

Internet Links for MereheaditeHide

Localities for MereheaditeHide

This map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.

Locality ListHide

- This locality has map coordinates listed. - This locality has estimated coordinates. ⓘ - Click for further information on this occurrence. ? - Indicates mineral may be doubtful at this locality. - Good crystals or important locality for species. - World class for species or very significant. (TL) - Type Locality for a valid mineral species. (FRL) - First Recorded Locality for everything else (eg varieties). Struck out - Mineral was erroneously reported from this locality. Faded * - Never found at this locality but inferred to have existed at some point in the past (eg from pseudomorphs.)

All localities listed without proper references should be considered as questionable.
Germany
 
  • Baden-Württemberg
    • Black Forest
      • Wolfach
        • Oberwolfach
          • Rankach valley
WALENTA, K. (1999): Neue Mineralfunde von der Grube Clara. 8. Folge, 2. Teil. Lapis 24 (12), 40-44; KOLITSCH, U. (2000): Eine durch Betoneinwirkung entstandene Paragenese von Blei-Verbindungen aus der Grube Clara im mittleren Schwarzwald. Erzgräber 14, 48-53. [discussion of the mereheadite reported by Walenta (1999)].
  • North Rhine-Westphalia
    • Sauerland
      • Brilon
Rouse, R. C. and Dunn, P. J. (1990): A new lead sulfate oxychloride related to the nadorite group from Brilon, Germany. Neues Jahrb. Mineral. Monatsh. 1990, 337-342; Turner, R.W., Siidra, O.I., Rumsey, M.S., Polekhovsky, Y.S., Kretser, Y.L., Krivovichev, S.V., Spratt, J., Stanley, C.J. (2015): Yeomanite, Pb2O(OH)Cl, a new chain-structured Pb oxychloride from Merehead Quarry, Somerset, England. Mineralogical Magazine, 79, 1203-1211.
UK
 
  • England
    • Bristol
      • Westbury on Trym
BMS Database
    • Somerset
      • Cranmore
[Mineralogical Magazine(1998) 62, 387-393; J. Russel Soc 2:2 p29]; Turner, R.W., (2005) A New Find of Lead Oxychlorides at Torr Works, Somerset. Russell Society Newsletter, No. 47, September 2005; Turner, R.W., (2006) A Mechanism for the formation of the Mineralised Mn Deposits at Merehead Quarry, Cranmore, Somerset, England. Mineralogical Magazine vol. 70, no. 6, pp 629 - 653; Krivovichev, S.V., Turner, R.W., Rumsey, M.S., Siidra, O.I. and Kirk, C.A. (2009). The crystal structure and chemistry of mereheadite. Mineralogical Magazine, 73, 75-89; Turner, R.W. and Rumsey, M.S. (2010): Mineral Relationships in the Mendip Hills. Journal of the Russell Society, vol 13, pp 3-46;
Mineral and/or Locality  
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