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Ecdemite

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About EcdemiteHide

Formula:
Pb6Cl4(As2O7)
the study of Perchiazzi et al. (2019, in press) shows ecdemite to be based on litharge-like defective layers. The layers formula is {Pb2[Pb4O](AsO3)2}4+.
Colour:
Greenish-yellow, yellow
Lustre:
Vitreous, Greasy
Hardness:
2½ - 3
Specific Gravity:
7.14
Crystal System:
Monoclinic
Name:
From the Greek έκδημος for "unusual" or "outstanding", in allusion to the composition.
Dimorph of:
A representative of layered lead oxyhalides group.


Classification of EcdemiteHide

Approved, 'Grandfathered' (first described prior to 1959)
3/D.10-100
3.DC.65

3 : HALIDES
D : Oxyhalides, hydroxyhalides and related double halides
C : With Pb (As,Sb,Bi), without Cu
46.2.1.1

46 : ANTIMONITES AND ARSENITES CONTAINING HYDROXYL OR HALOGEN
2 : Miscellaneous
23.7

23 : Arsenites

Physical Properties of EcdemiteHide

Vitreous, Greasy
Transparency:
Translucent
Comment:
Lustre vitreous on cleavages and greasy on fractures
Colour:
Greenish-yellow, yellow
Streak:
Light yellow
Hardness:
2½ - 3 on Mohs scale
Cleavage:
Distinct/Good
On {001}, distinct.
Density:
7.14 g/cm3 (Measured)    7.3 g/cm3 (Calculated)

Optical Data of EcdemiteHide

Type:
Uniaxial (-)
RI values:
nω = 2.320 nε = 2.250
Max Birefringence:
δ = 0.070
Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.
Surface Relief:
Very High

Chemical Properties of EcdemiteHide

Formula:
Pb6Cl4(As2O7)

the study of Perchiazzi et al. (2019, in press) shows ecdemite to be based on litharge-like defective layers. The layers formula is {Pb2[Pb4O](AsO3)2}4+.
IMA Formula:
Pb6As3+2O7Cl4

Crystallography of EcdemiteHide

Crystal System:
Monoclinic
Class (H-M):
2 - Sphenoidal
Space Group:
P21
Setting:
P21
Cell Parameters:
a = 10.82(4) Å, b = 10.826(2) Å, c = 6.97(1) Å
β = 113.26(2)°
Ratio:
a:b:c = 0.999 : 1 : 0.644
Unit Cell V:
750.09 ų (Calculated from Unit Cell)
Morphology:
Crystals small tabular and in foliated masses.
Comment:
from structure refinement by Perchiazzi et al. (2019, in press), Harstigen material; previously thought to be tetragonal.

Type Occurrence of EcdemiteHide

Synonyms of EcdemiteHide

Other Language Names for EcdemiteHide

Common AssociatesHide

Associated Minerals Based on Photo Data:
5 photos of Ecdemite associated with WulfenitePb(MoO4)
5 photos of Ecdemite associated with RhodoniteCaMn3Mn[Si5O15]
4 photos of Ecdemite associated with ParalaurionitePbCl(OH)
1 photo of Ecdemite associated with CerussitePbCO3

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.25BismocliteBiOClTet. 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.45MereheaditePb47Cl25(OH)13O24(CO3)(BO3)2Mon. m
3.DC.50BlixitePb8O5(OH)2Cl4Orth.
3.DC.55PinalitePb3WO5Cl2Orth.
3.DC.60SymesitePb10(SO4)O7Cl4 · H2OTric. 1 : P1
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

Related Minerals - Hey's Chemical Index of Minerals GroupingHide

23.2NanlingiteNa(Ca5Li)Mg12(AsO3)2[Fe(AsO3)6]F14Trig.
23.3LeiteiteZn(As2O4)Mon. 2/m : P21/b
23.5Kuznetsovite([Hg1+]2)Hg2+(AsO4)ClIso. 2 3 : P21 3
23.6PaulmooreitePb2[As2O5]Mon. 2/m : P21/b
23.9FinnemanitePb5(AsO3)3ClHex. 6/m : P63/m
23.10GebharditePb8(As2O5)2OCl6Mon. 2/m : P21/b
23.11Zimbabweite(Na,K)2PbAs4(Ta,Nb,Ti)4O18Orth.
23.13RouseitePb2Mn2+[AsO3]2 · 2H2OTric.
23.14FreediteCu+Pb8(AsO3)2O3Cl5Mon. 2/m : B2/m
23.15ManganarsiteMn3(As2O4)(OH)4Trig.
23.17ArmangiteMn2+26(AsO3)14(HAsO3)4(CO3)Trig. 3 : P3
23.18KaribibiteFe3+3(As3+O2)4(As3+2O5)(OH)Orth. mmm (2/m 2/m 2/m) : Pnma
23.19SchneiderhöhniteFe2+Fe3+3As3+5O13Tric. 1 : P1
23.20Lazarenkoite(Ca,Fe2+)Fe3+As3+3O7 · 3H2OOrth.
23.21StenhuggariteCaFeSb(AsO3)2OTet.
23.22Tomichite(V,Fe)4Ti3AsO13(OH)Mon.

Other InformationHide

Notes:
Soluble in HNO3 or warm HCl, and in alkalies.
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 EcdemiteHide

Reference List:
Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
Nordenskiöld, A.E. (1877) Geologiska Föeningens I Stockholm. Förhandlinger, Stockholm: 3: 379 (as Ekdemit).
Hamberg (1889) Geologiska Föeningens I Stockholm. Förhandlinger, Stockholm: 11: 229.
Larsen, E.S. (1921) The Microscopic Determination of the Nonopaque Minerals, First edition, USGS Bulletin 679: 71.
Sillén and Melander (1941) Zeitschrift für Kristallographie: 103: 420.
Palache, C., Berman, H., & Frondel, C. (1951), The System of Mineralogy of James Dwight Dana and Edward Salisbury Dana, Yale University 1837-1892, Volume II. John Wiley and Sons, Inc., New York, 7th edition, revised and enlarged, 1124 pp.: 1036-1037.
Welin, E. (1968) X-ray powder data for minerals from Långban and the related mineral deposits of Central Sweden. Arkiv för Mineralogi och Geologi, Stockholm: 4(30): 499–541.
Perchiazzi, N., Hålenius, U., Vignola, P., Demitri, N. (2019): Crystal-chemical study of ecdemite from Harstigen, a new natural member of the layered lead oxyhalides group. European Journal of Mineralogy: 31 (in press).

Internet Links for EcdemiteHide

Localities for EcdemiteHide

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.
China
 
  • Qinghai
    • Haixi Mongol and Tibetan Autonomous Prefecture
      • Da Qaidam (Dachaidan Co.)
        • Xitieshan
Li, W., and Chen, G. (1985): The discovery of heliophyllite in China. Acta Mineralogica Sinica 5(3), 216–220
Greece
 
  • Attica
    • East Attica
      • Lavreotiki
Schnorrer-Köhler, G., Standfuss, K. & Standfuss, L. (1981): Neufunde von Mineralen aus den antiken Bleischlacken Laurions. Der Aufschluss, 32, 165-169.
          • Panormos area
https://www.mineralienatlas.de/lexikon/index.php/Griechenland/Attika%20%28Attik%ED%2C%20Attica%29/Lavrion%20%28Laurion%29%2C%20Bergbaudistrikt/Schlackenfundstellen/Panormos
          • Passa Limani area
Gelaude, Piet, van Kalmthout, Piet, and Rewitzer, Christian (1996) Laurion: The Minerals of the Ancient Slags, Janssen Print, Nijmegen, The Netherlands
          • Sounion area
Laurion The minerals in the ancient slags by Piet Gelaude etc.
Lauarion the minerals in the ancient slags by Piet Gelaude etc.
Gelaude, Piet, van Kalmthout, Piet and Rewitzer, Christian, (1996) Laurion: The Minerals in the Ancient Slags, Janssen Print, Nijmegen, The Netherlands
          • Thorikos area
Gelaude, Piet, van Kalmthout, Piet and Rewitzer, Christian (1996) Laurion: The Minerals in the Ancient Slags, Janssen Print, Nijmegen, The Netherlands
          • Vrissaki area
Gelaude, Piet, van Kalmthout, Piet, and Rewitzer, Christian (1996) Laurion: The Minerals in the Ancient Slags, Janssen Print, Nijmegen, The Netherlands
Italy
 
  • Tuscany
    • Livorno Province
      • Campigliese (Campiglia Mountains; Campiglia Ridge)
        • Campiglia Marittima
          • Madonna di Fucinaia (Madonna della Fucinaia) slag heaps
http://www.comune.pisa.it/apsn/Articoli/Scorie/Capattoli.htm
      • Piombino
Muenchener Micromounter-Lithothek
Sweden (TL)
 
  • Värmland County
    • Filipstad
Geologiska Föreningens I Stockholm. Förhandlinger, Stockholm (1877) 3, 379; Palache, C., Berman, H., & Frondel, C. (1951), The System of Mineralogy of James Dwight Dana and Edward Salisbury Dana, Yale University 1837-1892, Volume II: 1036; Nysten, P., Holtstam, D. and Jonsson, E. (1999) The Långban minerals. In Långban - The mines,their minerals, geology and explorers (D. Holtstam and J. Langhof, eds.), Swedish Museum of Natural History and Raster Förlag, Stockholm & Chr. Weise Verlag, Munich, pp. 89-183.
      • Nordmark District
        • Jakobsberg ore field
Palache, C., Berman, H., & Frondel, C. (1951), The System of Mineralogy of James Dwight Dana and Edward Salisbury Dana, Yale University 1837-1892, Volume II: 1037.
      • Persberg ore district
        • Pajsberg
GFF 125 (2003) 2, 87-98; Nysten, P. (1984): Kleinod des Nordens - Harstigen in Schweden. Magma 2/1984, 12-30.
No reference listed
USA
 
  • California
    • Inyo Co.
      • Argus Mts (Argus Range)
        • Lookout Mining District (Modoc Mining District)
          • Lookout City
; Murdoch, Joseph & Robert W. Webb (1966), Minerals of California, Centennial Volume (1866-1966): California Division Mines & Geology Bulletin 189: 173; Pemberton, H. Earl (1983), Minerals of California; Van Nostrand Reinholt Press: 325.
  • Montana
    • Madison Co.
      • Rochester Mining District (Rabbit Mining District)
USGS Bull 574
USGS Bull 574
  • Nevada
    • Clark Co.
      • Spring Mountains
        • Goodsprings Mining District
NBMG Spec. Pub. 31 Minerals of Nevada
 
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