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Ecdemite

A valid IMA mineral species - grandfathered
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About EcdemiteHide

Formula:
Pb6Cl4(As2O7)
the study of Perchiazzi et al. (2019) 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 έÎșÎŽÎ·ÎŒÎżÏ‚ for "unusual" or "outstanding", in allusion to the composition.
A representative of layered lead oxyhalides group.


Unique IdentifiersHide

Mindat ID:
1363
Long-form identifier:
mindat:1:1:1363:1
GUID
(UUID V4):
b27b40f9-da76-4dab-bcbf-811e7e284744

IMA Classification of EcdemiteHide

Approved, 'Grandfathered' (first described prior to 1959)
IMA Formula:
Pb6As2O7Cl4

Classification of EcdemiteHide

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

Mineral SymbolsHide

As of 2021 there are now IMA–CNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.

SymbolSourceReference
EcdIMA–CNMNCWarr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43

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

Chemistry of EcdemiteHide

Mindat Formula:
Pb6Cl4(As2O7)

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

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), Harstigen material; previously thought to be tetragonal.

X-Ray Powder DiffractionHide

Powder Diffraction Data:
d-spacingIntensity
2.85 Å(100)
3.66 Å(80)
2.72 Å(80)
2.07 Å(70)
1.591 Å(70)
1.92 Å(60)
1.652 Å(50)
Comments:
LĂ„ngban mine, Sweden.

Type Occurrence of EcdemiteHide

Synonyms of EcdemiteHide

Other Language Names for EcdemiteHide

Common AssociatesHide

Associated Minerals Based on Photo Data:
10 photos of Ecdemite associated with ParalaurionitePbCl(OH)
9 photos of Ecdemite associated with RhodoniteCaMn3Mn[Si5O15]
8 photos of Ecdemite associated with PhosgenitePb2CO3Cl2
5 photos of Ecdemite associated with WulfenitePb(MoO4)
5 photos of Ecdemite associated with FluoriteCaF2
4 photos of Ecdemite associated with CalciteCaCO3
4 photos of Ecdemite associated with LaurionitePbCl(OH)
3 photos of Ecdemite associated with CerussitePbCO3
3 photos of Ecdemite associated with AragoniteCaCO3
2 photos of Ecdemite associated with AnglesitePbSO4

Related Minerals - Strunz-mindat GroupingHide

3.DC.Lucabindiite(K,NH4)As4O6(Cl,Br)Hex. 6/mmm (6/m 2/m 2/m) : P6/mmm
3.DC.TorrecillasiteNa(As,Sb)3+4O6ClOrth.
3.DC.GajardoiteKCa0.5As3+4O6Cl2 · 5H2OHex. 6/mmm (6/m 2/m 2/m) : P6/mmm
3.DC.Cuatrocapaite-(NH₄)(NH4)3(NaMg◻)(As2O3)6Cl6 · 16H2OTrig. 3m (3 2/m) : R3m
3.DC.Cuatrocapaite-(K)K3(NaMg◻)(As2O3)6Cl6 · 16H2OTrig. 3m (3 2/m) : R3m
3.DC.NapoliitePb2OFClTet. 4/mmm (4/m 2/m 2/m) : P42/mcm
3.DC.05LaurionitePbCl(OH)Orth. mmm (2/m 2/m 2/m)
3.DC.05ParalaurionitePbCl(OH)Mon. 2/m : B2/m
3.DC.05Russoite(NH4)ClAs2O3(H2O)0.5Hex. 6 2 2 : P6 2 2
3.DC.05Mauriziodiniite(NH4)(As2O3)2IHex. 6/mmm (6/m 2/m 2/m) : P6/mmm
3.DC.10FiedleritePb3FCl4(OH) · H2OMon. 2/m
3.DC.15PenfielditePb2Cl3(OH)Hex. 6 : P6
3.DC.15TelluroperitePb3TeO4Cl2Orth. mmm (2/m 2/m 2/m)
3.DC.20LaurelitePb7F12Cl2Hex. 6 : P6
3.DC.25BismocliteBiOClTet. 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. 4/mmm (4/m 2/m 2/m) : P4/nmm
3.DC.25Zavaritskite(BiO)FTet. 4/mmm (4/m 2/m 2/m) : P4/nmm
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.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.52RumseyitePb2OClF Tet. 4/mmm (4/m 2/m 2/m) : I4/mmm
3.DC.55PinalitePb3WO5Cl2Orth. mmm (2/m 2/m 2/m)
3.DC.55Vladkrivovichevite[Pb32O18][Pb4Mn2O]Cl14(BO3)8 · 2H2O Orth. mmm (2/m 2/m 2/m) : Pmmn
3.DC.57YeomanitePb2O(OH)ClOrth. mmm (2/m 2/m 2/m) : Pnma
3.DC.60LorettoitePb7O6Cl2Orth.
3.DC.60SymesitePb10(SO4)O7Cl4 · H2OTric. 1 : P1
3.DC.62Sarawakite (of Frenzel)Sb, O, Cl (?)
3.DC.70MendipitePb3Cl2O2Orth. 2 2 2 : P21 21 21
3.DC.75DamaraitePb3Cl(OH)O2Orth. mm2 : Pmc21
3.DC.80OnoratoiteSb8Cl2O11Tric. 1 : P1
3.DC.95BarstowitePb4Cl6(CO3) · H2OMon. 2/m : P21/m

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.

Internet Links for EcdemiteHide

References for EcdemiteHide

Reference List:

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 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.
China
 
  • Qinghai
    • Haixi Mongol and Tibetan Autonomous Prefecture
      • Da Qaidam (Dachaidan Co.)
        • Xitieshan
Li et al. (1985)
Greece
 
  • Attica
    • East Attica
      • Lavreotiki
Schnorrer-Köhler et al. (1981)
Gelaude et al. (1996)
Gelaude et al. (1996)
www.mineralienatlas.de (2014)
Gelaude et al. (1996)
Gelaude et al. (1996)
Gelaude et al. (1996)
Gelaude et al. (1996)
Italy
 
  • Tuscany
    • Livorno Province
      • Campiglia Marittima
        • Madonna di Fucinaia (Madonna della Fucinaia) slag heaps
www.comune.pisa.it (2000)
      • Piombino
Muenchener Micromounter-Lithothek
Spain
 
  • Murcia
    • MazarrĂłn
Van der Berg et al. (2020)
Sweden (TL)
 
  • VĂ€rmland County
    • Filipstad
      • LĂ„ngban Ore District
Geologiska Föreningens I Stockholm. Förhandlinger (1877) +2 other references
      • Nordmark mining district
        • Jakobsberg ore field
Sillén et al. (1941) +2 other references
      • Persberg ore district
        • Pajsberg
Flink (1888) +2 other references
USA
 
  • California
    • Inyo County
      • Argus Mts (Argus Range)
        • Lookout Mining District (Modoc Mining District)
          • Lookout City
Van Nostrand Reinholt Press: 325. +2 other references
  • Montana
    • Madison County
      • Rochester Mining District (Rabbit Mining District)
Winchell (1914)
Winchell (1914)
  • Nevada
    • Clark County
      • Spring Mountains
        • Goodsprings Mining District
Castor et al. (2004)
 
Mineral and/or Locality  
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