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Ecdemite

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Big Photo

Harstigen Mine, Pajsberg, Persberg district, Filipstad, Värmland, Sweden
© Kjell Gatedal

Show Ecdemite Photos (10)



Formula:
Pb
 
6
Cl
 
4
(As
 
2
O
 
7
)
System:TetragonalColour:Greenish-yellow, yellow
Lustre:Vitreous, GreasyHardness:2½ - 3
Name:From the Greek έκδημος for "unusual" or "outstanding", in allusion to the composition.
Dimorph of:Heliophyllite


Apparently dimorphous with Heliophyllite.

Classification of Ecdemite

IMA status:Valid - first described prior to 1959 (pre-IMA) - "Grandfathered"
Strunz 8th edition ID:3/D.10-100
Nickel-Strunz 10th (pending) edition ID:3.DC.65

3 : HALIDES
D : Oxyhalides, hydroxyhalides and related double halides
C : With Pb (As,Sb,Bi), without Cu
Dana 8th edition ID:46.2.1.1

46 : ANTIMONITES AND ARSENITES CONTAINING HYDROXYL OR HALOGEN
2 : Miscellaneous
Hey's CIM Ref.:23.7

23 : Arsenites
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Type Occurrence of Ecdemite

Type Locality:Långban, Filipstad, Värmland, Sweden
Year of Discovery:1877
Geological Setting of type material:Metamorphosed Fe-Mn ore body.
Associated Minerals at type locality:
Manganoan CalciteMagnetiteLeadHeliophylliteFreedite
FinnemaniteCopperAndradite

Physical Properties of Ecdemite

Lustre: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 (measured):7.14 g/cm3
Density (calculated):7.3 g/cm3

Crystallography of Ecdemite

Crystal System:Tetragonal
Cell Parameters:a = 10.82Å, c = 25.6Å
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.

Optical Data of Ecdemite

Type:Uniaxial (-)
RI values: nω = 2.320 nε = 2.250
Maximum Birefringence:δ = 0.070

Chart 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:
Pb
 
6
Cl
 
4
(As
 
2
O
 
7
)
Essential elements:As, Cl, O, Pb
All elements listed in formula:As, Cl, O, Pb

Relationship of Ecdemite to other Species

Related Minerals - Nickel-Strunz Grouping):

- +
3.DC.05Laurionite
PbCl(OH)
3.DC.05Paralaurionite
PbCl(OH)
3.DC.10Fiedlerite
Pb
 
3
FCl
 
4
(OH) · H
 
2
O
3.DC.15Penfieldite
Pb
 
2
Cl
 
3
(OH)
3.DC.20Laurelite
Pb
 
7
F
 
12
Cl
 
2
3.DC.25Bismoclite
(BiO)Cl
3.DC.25Daubréeite
(BiO)(OH,Cl)
3.DC.25Matlockite
PbFCl
3.DC.25Rorisite
CaFCl
3.DC.25Zavaritskite
(BiO)F
3.DC.25Zhangpeishanite
BaFCl
3.DC.30Nadorite
PbSbClO
 
2
3.DC.30Perite
PbBiClO
 
2
3.DC.35Aravaipaite
Pb
 
3
F
 
3
[AlF
 
6
] · H
 
2
O
3.DC.37Calcioaravaipaite
PbCa
 
2
AlF
 
9
3.DC.40Thorikosite
Pb
 
3
Cl
 
2
(OH)(SbO
 
3
,AsO
 
3
)
3.DC.45Mereheadite
Pb
 
47
Cl
 
25
(OH)
 
13
O
 
24
(CO
 
3
)(BO
 
3
)
 
2
3.DC.50Blixite
Pb
 
2
(O,OH)
 
2
Cl
3.DC.55Pinalite
Pb
 
3
WO
 
5
Cl
 
2
3.DC.60Symesite
Pb
 
10
(SO
 
4
)O
 
7
Cl
 
4
 · H
 
2
O
3.DC.65Heliophyllite
Pb
 
6
Cl
 
4
(As
 
2
O
 
7
)
3.DC.70Mendipite
Pb
 
3
Cl
 
2
O
 
2
3.DC.75Damaraite
Pb
 
3
Cl(OH)O
 
2
3.DC.80Onoratoite
Sb
 
8
Cl
 
2
O
 
11
3.DC.85Cotunnite
PbCl
 
2
3.DC.90Pseudocotunnite
K
 
2
PbCl
 
4
3.DC.95Barstowite
Pb
 
4
Cl
 
6
(CO
 
3
) · H
 
2
O
Related Minerals - Hey's Index Grouping:

- +
23.2Nanlingite
NaMg
 
4
(AsO
 
3
)
 
2
F
 
4
23.3Leiteite
Zn(As
 
2
O
 
4
)
23.5Kuznetsovite
(Hg
+
2
)Hg
2+
 
(AsO
 
4
)Cl
23.6Paulmooreite
Pb
 
2
[As
 
2
O
 
5
]
23.8Heliophyllite
Pb
 
6
Cl
 
4
(As
 
2
O
 
7
)
23.9Finnemanite
Pb
 
5
(AsO
 
3
)
 
3
Cl
23.10Gebhardite
Pb
 
8
(As
 
2
O
 
5
)
 
2
OCl
 
6
23.11Zimbabweite
(Na,K)
 
2
PbAs
 
4
(Ta,Nb,Ti)
 
4
O
 
18
23.13Rouseite
Pb
 
2
Mn
2+
 
[AsO
 
3
]
 
2
 · 2H
 
2
O
23.14Freedite
Cu
+
 
Pb
 
8
(AsO
 
3
)
 
2
O
 
3
Cl
 
5
23.15Manganarsite
Mn
 
3
(As
 
2
O
 
4
)(OH)
 
4
23.17Armangite
Mn
2+
26
(AsO
 
3
)
 
14
(HAsO
 
3
)
 
4
(CO
 
3
)
23.18Karibibite
Fe
 
2
As
 
4
O
 
9
23.19Schneiderhöhnite
Fe
2+
 
Fe
3+
3
[As
 
5
O
 
13
]
23.20Lazarenkoite
(Ca,Fe
2+
 
)Fe
3+
 
As
3+
3
O
 
7
 · 3H
 
2
O
23.21Stenhuggarite
CaFeSb(AsO
 
3
)
 
2
O
23.22Tomichite
(V,Fe)
 
4
Ti
 
3
AsO
 
13
(OH)

Other Names for Ecdemite

Synonyms:
Ekdemite
Other Languages:
German:Ecdemit
Ekdemit
Spanish:Ecdemita
Ekdemita

Other Information

Other Information:Soluble in HNO3 or warm HCl, and in alkalies.
Health Warning: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

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  • Raman and XRD data at RRUFF project
  • American Mineralogist Crystal Structure Database
  • Ecdemite details from Handbook of Mineralogy (PDF)
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    • Localities for Ecdemite

    The 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.
    Hide Locality List
    (TL) indicates type locality. ? 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 (Attica; Attika) Prefecture
      • Lavrion (Laurion; Laurium) District
    		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
    		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
     
    • 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; 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.
    No reference listed
    USA
     
    • California
      • Inyo Co.
        • Lookout District (Modoc District)
          • Panamint Valley
    		; 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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    Copyright © Jolyon Ralph and Ida Chau 1993-2013. Site Map. Locality, mineral & photograph data are the copyright of the individuals who submitted them. Further information contact the Site hosted & developed by Jolyon Ralph. Mindat.org is an online information resource dedicated to providing free mineralogical information to all. Mindat relies on the contributions of hundreds of members and supporters. Mindat does not offer minerals for sale. If you would like to add information to improve the quality of our database, then click here to register.
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