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Ecdemite

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Formula:
Pb6Cl4(As2O7)
System:
Tetragonal
Colour:
Greenish-yellow, yellow
Lustre:
Vitreous, Greasy
Hardness:
2½ - 3
Name:
From the Greek έκδημος for "unusual" or "outstanding", in allusion to the composition.
Dimorph of:
Apparently dimorphous with Heliophyllite.


Classification of Ecdemite

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 Ecdemite

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

Optical Data of Ecdemite

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 Ecdemite

Formula:
Pb6Cl4(As2O7)
IMA Formula:
Pb6As23+O7Cl4
Elements listed in formula:

Crystallography of Ecdemite

Crystal System:
Tetragonal
Cell Parameters:
a = 10.82 Å, c = 25.6 Å
Ratio:
a:c = 1 : 2.366
Unit Cell Volume:
V 2,997.05 ų (Calculated from Unit Cell)
Z:
8
Morphology:
Crystals small tabular and in foliated masses.

Type Occurrence of Ecdemite

Geological Setting of Type Material:
Metamorphosed Fe-Mn ore body.

Relationship of Ecdemite to other Species

3.DC.05LaurionitePbCl(OH)
3.DC.05ParalaurionitePbCl(OH)
3.DC.10FiedleritePb3FCl4(OH) · H2O
3.DC.15PenfielditePb2Cl3(OH)
3.DC.20LaurelitePb7F12Cl2
3.DC.25Bismoclite(BiO)Cl
3.DC.25Daubréeite(BiO)(OH,Cl)
3.DC.25MatlockitePbFCl
3.DC.25RorisiteCaFCl
3.DC.25Zavaritskite(BiO)F
3.DC.25ZhangpeishaniteBaFCl
3.DC.30NadoritePbSbClO2
3.DC.30PeritePbBiClO2
3.DC.35AravaipaitePb3AlF9 · H2O
3.DC.37CalcioaravaipaitePbCa2AlF9
3.DC.40ThorikositePb3Cl2(OH)(SbO3,AsO3)
3.DC.45MereheaditePb47Cl25(OH)13O24(CO3)(BO3)2
3.DC.50BlixitePb2(O,OH)2Cl
3.DC.55PinalitePb3WO5Cl2
3.DC.60SymesitePb10(SO4)O7Cl4 · H2O
3.DC.65HeliophyllitePb6Cl4(As2O7)
3.DC.70MendipitePb3Cl2O2
3.DC.75DamaraitePb3Cl(OH)O2
3.DC.80OnoratoiteSb8Cl2O11
3.DC.85CotunnitePbCl2
3.DC.90PseudocotunniteK2PbCl4
3.DC.95BarstowitePb4Cl6(CO3) · H2O
23.2NanlingiteNa(Ca5Li)Mg12(AsO3)2[Fe(AsO3)6]F14
23.3LeiteiteZn(As2O4)
23.5Kuznetsovite(Hg2+)Hg2+(AsO4)Cl
23.6PaulmooreitePb2[As2O5]
23.8HeliophyllitePb6Cl4(As2O7)
23.9FinnemanitePb5(AsO3)3Cl
23.10GebharditePb8(As2O5)2OCl6
23.11Zimbabweite(Na,K)2PbAs4(Ta,Nb,Ti)4O18
23.13RouseitePb2Mn2+[AsO3]2 · 2H2O
23.14FreediteCu+Pb8(AsO3)2O3Cl5
23.15ManganarsiteMn3(As2O4)(OH)4
23.17ArmangiteMn262+(AsO3)14(HAsO3)4(CO3)
23.18KaribibiteFe3+(As3+O2)4(As23+O5)(OH)
23.19SchneiderhöhniteFe2+Fe33+[As5O13]
23.20Lazarenkoite(Ca,Fe2+)Fe3+As33+O7 · 3H2O
23.21StenhuggariteCaFeSb(AsO3)2O
23.22Tomichite(V,Fe)4Ti3AsO13(OH)

Other Names for Ecdemite

Name in Other Languages:

Other Information

Other Information:
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 Ecdemite

Reference List:
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.

Internet Links for Ecdemite

mindat.org URL:
https://www.mindat.org/min-1363.html
Please feel free to link to this page.

Localities for Ecdemite

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.
(TL) indicates type locality for a valid mineral species. (FRL) indicates first recorded locality for everything else. ? indicates mineral may be doubtful at this locality. All other localities listed without reference should be considered as uncertain and unproven until references can be found.
Greece
 
  • Attikí Prefecture (Attica; Attika)
    • Lavrion District (Laurion; Laurium)
Schnorrer-Köhler, G., Standfuss, K. & Standfuss, L. (1981): Neufunde von Mineralen aus den antiken Bleischlacken Laurions. Der Aufschluss, 32, 165-169.
        • 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
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
      • Piombino
Muenchener Micromounter-Lithothek
Sweden (TL)
 
  • Värmland
    • Filipstad
Geologiska Föeningens 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.
      • Persberg 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 District (Modoc 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 District (Rabbit District)
USGS Bull 574
USGS Bull 574
Mineral and/or Locality  
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