Mereheadite
A valid IMA mineral species
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About Mereheadite
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:
3½
Specific Gravity:
7.12
Crystal System:
Monoclinic
Name:
Named after Merehead quarry, Somerset, the source of this and other unusual lead secondary minerals.
Type Locality:
Unique Identifiers
Mindat ID:
2648
Long-form identifier:
mindat:1:1:2648:8
GUID
(UUID V4):
(UUID V4):
53ec3e74-441e-4f23-906e-faa554aa2f5a
IMA Classification of Mereheadite
Classification of Mereheadite
3.DC.45
3 : HALIDES
D : Oxyhalides, hydroxyhalides and related double halides
C : With Pb (As,Sb,Bi), without Cu
3 : HALIDES
D : Oxyhalides, hydroxyhalides and related double halides
C : With Pb (As,Sb,Bi), without Cu
Mineral Symbols
As of 2021 there are now IMA–CNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.
Symbol | Source | Reference |
---|---|---|
Mrh | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
Physical Properties of Mereheadite
Vitreous, Resinous
Transparency:
Transparent, Translucent
Colour:
Pale yellow to reddish-orange
Streak:
White
Hardness:
3½ on Mohs scale
Tenacity:
Brittle
Cleavage:
Perfect
(001)
(001)
Fracture:
Hackly, Conchoidal
Density:
7.12 g/cm3 (Measured) 7.31 g/cm3 (Calculated)
Optical Data of Mereheadite
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.
and does not take into account mineral colouration.
Surface Relief:
Moderate
Dispersion:
relatively strong
Reflectivity:
Wavelength | R1 | R2 |
---|---|---|
400nm | 17.20% | 17.95% |
420nm | 16.50% | 17.40% |
440nm | 15.90% | 16.90% |
460nm | 15.50% | 16.50% |
480nm | 15.10% | 16.10% |
500nm | 14.90% | 15.80% |
520nm | 14.50% | 15.50% |
540nm | 14.30% | 15.30% |
560nm | 14.10% | 15.20% |
580nm | 14.00% | 15.00% |
600nm | 13.90% | 14.90% |
620nm | 13.80% | 14.80% |
640nm | 13.80% | 14.80% |
660nm | 13.70% | 14.70% |
680nm | 13.60% | 14.65% |
700nm | 13.60% | 14.60% |
Graph shows reflectance levels at different wavelengths (in nm). Top of box is 100%. Peak reflectance is 17.95%.
R1 shown in black, R2 shown in red
Colour in reflected light:
Gray
Internal Reflections:
Light yellow
Pleochroism:
Non-pleochroic
Chemistry of Mereheadite
Mindat Formula:
Pb47Cl25(OH)13O24(CO3)(BO3)2
Formula originally assumed to be Pb2O(OH)Cl.
Formula originally assumed to be Pb2O(OH)Cl.
Crystallography of Mereheadite
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)°
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°.
Crystal Structure
Load
Unit Cell | Unit Cell Packed
2x2x2 | 3x3x3 | 4x4x4
Unit Cell | Unit Cell Packed
2x2x2 | 3x3x3 | 4x4x4
Show
Big Balls | Small Balls | Just Balls | Spacefill
Polyhedra Off | Si Polyhedra | All Polyhedra
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Big Balls | Small Balls | Just Balls | Spacefill
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2D | Stereo | Red-Blue | Red-Cyan
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View
CIF File Best | x | y | z | a | b | c
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Rotation
Stop | Start
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Labels
Console Off | On | Grey | Yellow
Console Off | On | Grey | Yellow
Data courtesy of the American Mineralogist Crystal Structure Database. Click on an AMCSD ID to view structure
ID | Species | Reference | Link | Year | Locality | Pressure (GPa) | Temp (K) |
---|---|---|---|---|---|---|---|
0014589 | Mereheadite | Krivovichev S V, Turner R, Rumsey M, Sidra O I, Kirk C A (2009) The crystal structure and chemistry of mereheadite Mineralogical Magazine 73 103-117 | 2009 | Merehead Quarry, Cranmore, Somerset, England | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
d-spacing | Intensity |
---|---|
2.930 Å | (100) |
3.785 Å | (48) |
2.825 Å | (43) |
6.581 Å | (37) |
2.182 Å | (37) |
2.780 Å | (36) |
3.267 Å | (35) |
Comments:
Merehead Quarry, Somerset, England. Data from the type description.
Geological Environment
Paragenetic Mode(s):
Paragenetic Mode | Earliest Age (Ga) |
---|---|
Stage 7: Great Oxidation Event | <2.4 |
47c : [Carbonates, phosphates, borates, nitrates] | |
47e : [Vanadates, chromates, manganates] | |
47g : [Halogen-bearing surface weathering minerals] |
Type Occurrence of Mereheadite
General Appearance of Type Material:
Polycrystalline aggregates, up to 10 x 30 mm, in which individual grains are anhedral and rarely exceed 2 mm.
Place of Conservation of Type Material:
Natural History Museum, London, England, specimen BM 1965,285 and polished mount E.1175.
Geological Setting of Type Material:
Lead bearing lenses and cavities in veins of manganese and iron oxide minerals that cut through a sequence of dolomitic limestone.
Associated Minerals at Type Locality:
Synonyms of Mereheadite
Other Language Names for Mereheadite
German:Mereheadit
Spanish:Mereheadita
Common Associates
Associated Minerals Based on Photo Data:
22 photos of Mereheadite associated with Mendipite | Pb3Cl2O2 |
9 photos of Mereheadite associated with Rickturnerite | Pb7O4[Mg(OH)4](OH)Cl3 |
8 photos of Mereheadite associated with Chloroxiphite | Pb3CuO2Cl2(OH)2 |
7 photos of Mereheadite associated with Crednerite | CuMnO2 |
3 photos of Mereheadite associated with Paralaurionite | PbCl(OH) |
3 photos of Mereheadite associated with Symesite | Pb10(SO4)O7Cl4 · H2O |
3 photos of Mereheadite associated with Plumbonacrite | Pb5O(OH)2(CO3)3 |
3 photos of Mereheadite associated with Mimetite | Pb5(AsO4)3Cl |
3 photos of Mereheadite associated with Hydrocerussite | Pb3(CO3)2(OH)2 |
3 photos of Mereheadite associated with Parkinsonite | Pb7MoO9Cl2 |
Related Minerals - Strunz-mindat Grouping
3.DC. | Lucabindiite | (K,NH4)As4O6(Cl,Br) |
3.DC. | Torrecillasite | Na(As,Sb)3+4O6Cl |
3.DC. | Gajardoite | KCa0.5As3+4O6Cl2 · 5H2O |
3.DC. | Cuatrocapaite-(NH₄) | (NH4)3(NaMg◻)(As2O3)6Cl6 · 16H2O |
3.DC. | Cuatrocapaite-(K) | K3(NaMg◻)(As2O3)6Cl6 · 16H2O |
3.DC. | Napoliite | Pb2OFCl |
3.DC.05 | Laurionite | PbCl(OH) |
3.DC.05 | Paralaurionite | PbCl(OH) |
3.DC.05 | Russoite | (NH4)ClAs2O3(H2O)0.5 |
3.DC.05 | Mauriziodiniite | (NH4)(As2O3)2I |
3.DC.10 | Fiedlerite | Pb3FCl4(OH) · H2O |
3.DC.15 | Penfieldite | Pb2Cl3(OH) |
3.DC.15 | Telluroperite | Pb3TeO4Cl2 |
3.DC.20 | Laurelite | Pb7F12Cl2 |
3.DC.25 | Bismoclite | BiOCl |
3.DC.25 | Matlockite | PbFCl |
3.DC.25 | Rorisite | CaFCl |
3.DC.25 | Zavaritskite | (BiO)F |
3.DC.25 | Zhangpeishanite | BaFCl |
3.DC.30 | Nadorite | PbSbClO2 |
3.DC.30 | Perite | PbBiClO2 |
3.DC.40 | Thorikosite | Pb3Cl2(OH)(SbO3,AsO3) |
3.DC.50 | Blixite | Pb8O5(OH)2Cl4 |
3.DC.52 | Rumseyite | Pb2OClF |
3.DC.55 | Pinalite | Pb3WO5Cl2 |
3.DC.55 | Vladkrivovichevite | [Pb32O18][Pb4Mn2O]Cl14(BO3)8 · 2H2O |
3.DC.57 | Yeomanite | Pb2O(OH)Cl |
3.DC.60 | Lorettoite | Pb7O6Cl2 |
3.DC.60 | Symesite | Pb10(SO4)O7Cl4 · H2O |
3.DC.62 | Sarawakite (of Frenzel) | Sb, O, Cl (?) |
3.DC.65 | Ecdemite | Pb6Cl4(As2O7) |
3.DC.70 | Mendipite | Pb3Cl2O2 |
3.DC.75 | Damaraite | Pb3Cl(OH)O2 |
3.DC.80 | Onoratoite | Sb8Cl2O11 |
3.DC.95 | Barstowite | Pb4Cl6(CO3) · H2O |
Fluorescence of Mereheadite
Not fluorescent.
Other Information
Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.
Internet Links for Mereheadite
mindat.org URL:
https://www.mindat.org/min-2648.html
Please feel free to link to this page.
Please feel free to link to this page.
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References for Mereheadite
Reference List:
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 (3) 387-393 doi:10.1180/002646198547657
Localities for Mereheadite
Locality List
- This locality has map coordinates listed.
- This locality has estimated coordinates.
ⓘ - Click for references and 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 (e.g. from pseudomorphs).
All localities listed without proper references should be considered as questionable.
All localities listed without proper references should be considered as questionable.
Argentina | |
| Grundmann et al. (2018) |
| Grundmann et al. (2018) |
Germany | |
| Walenta (1999) +1 other reference |
| Rouse et al. (1990) +1 other reference |
UK | |
| Day (1999) |
| Alabaster (1989) +7 other references |
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Torr Works Quarry, Cranmore, Mendip, Somerset, England, UK