Ecdemite Mineral Data

Ecdemite Mineral Data +

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General Ecdemite Information

Chemical Formula:

Pb6As+++2O7Cl4

Composition:

Molecular Weight = 1,646.85 gm

Arsenic 9.10 % As 12.01 % As₂O₃

Lead 75.49 % Pb 81.32 % PbO

Chlorine 8.61 % Cl 8.61 % Cl

- % Cl -1.94 % -O=Cl₂

Oxygen 6.80 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

Pb₆As₂O₇Cl₄

IMA Status:

Valid Species (Pre-IMA) 1877

Locality:

Langban and Harstig mines, Varmland, Sweden. Link to MinDat.org Location Data.

Name Origin:

Named from the Greek for "unusual", in reference to the composition.

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Ecdemite Crystallography

Axial Ratios:

a:c = 1:2.37222

Cell Dimensions:

a = 10.8, c = 25.62, Z = 8; V = 2,988.32 Den(Calc)= 7.32

Crystal System:

TetragonalSpace Group: Unk

$Help on X Ray Diffraction:$ X Ray Diffraction:

By Intensity(I/I_o): 2.85(1), 2.72(0.8), 3.66(0.8),

Physical Properties of Ecdemite

Cleavage:

[001] Perfect

Color:

Green yellow, Yellow, Orange.

Density:

6.9 - 7.1, Average = 7

Diaphaniety:

Translucent

Habit:

Encrustations - Forms crust-like aggregates on matrix.

Habit:

Massive - Uniformly indistinguishable crystals forming large masses.

Habit:

Tabular - Form dimensions are thin in one direction.

Hardness:

2.5 - Finger Nail

Luminescence:

Non-fluorescent.

Luster:

Vitreous - Greasy

Magnetism:

Nonmagnetic

Streak:

light yellow

Optical Properties of Ecdemite

Gladstone-Dale:

CI meas= -0.122 (Poor) - where the CI = (1-KPDmeas/KC)
CI calc= -0.073 (Fair) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.1755,KPDmeas= 0.1836,KC= 0.1636

Optical Data:

Uniaxial (-), e=2.25, w=2.32, bire=0.0700.

Calculated Properties of Ecdemite

Electron Density:

r_electron=6.06 gm/cc
note: r_Ecdemite=7.32 gm/cc.

Fermion Index

Fermion Index = 0.16686
Boson Index = 0.83314

Photoelectric:

PE_Ecdemite=1,406.90 barns/electron
U=PE_Ecdemite x r_electron=8,529.71 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Ecdemite is Not Radioactive

Ecdemite Classification

Dana Class:

46.2.1.1 (46)Basic or Halogen-Containing Antimonites, Arsenites and Phosphites

(46.2)with miscellaneous formulae

(46.2.1)Dana Group

46.2.1.1 Ecdemite Pb6As2O7Cl4 Unk Tetra

Strunz Class:

III/D.11-110 III - Halogenides

III/D - Oxi-halogenides with Pb - Bi - Sb and related compounds

III/D.11 - Mendipite - Onoratoite series

III/D.11-10 Mendipite Pb3Cl2O2 P 2₁2₁2₁ 2 2 2

III/D.11-15 Damaraite Pb3O2(OH)Cl Pmc2 mm2

III/D.11-17 Chubutite* Pb7O6Cl2 Unk Ortho

III/D.11-20 Penfieldite Pb2Cl3(OH) P 6/mmm 6/m 2/m 2/m

III/D.11-30 Blixite Pb2Cl(O,OH)2 Unk Ortho

III/D.11-35 Mereheadite! Pb2O(OH)Cl C 2/c 2/m

III/D.11-40 Sundiusite Pb10(SO4)Cl2O8 C 2,Cm,C 2/m Mono

III/D.11-50 Asisite Pb12(SiO4)O8Cl4 I 4/mmm 4/m 2/m 2/m

III/D.11-55 Parkinsonite (Pb,Mo,[])8O8Cl2 I 4/mmm 4/m 2/m 2/m

III/D.11-60 Thorikosite Pb3(Sb,As)O3(OH)Cl2 I 4/mmm 4/m 2/m 2/m

III/D.11-65 Philolithite! Pb12O6Mn(Mg,Mn)2(Mn,Mg)4(SO4)(CO3)4Cl4(OH)12 P 4₁/nnm 4/m 2/m 2/m

III/D.11-70 Pinalite Pb3(WO4)OCl2 Amam 2/m 2/m 2/m

III/D.11-80 Nadorite PbSbO2Cl Bmmb 2/m 2/m 2/m

III/D.11-90 Perite PbBiO2Cl Bmmb 2/m 2/m 2/m

III/D.11-100 Heliophyllite Pb6As2O7Cl4 Unk Ortho

III/D.11-110 Ecdemite Pb6As2O7Cl4 Unk Tetra

III/D.11-120 Onoratoite Sb8O11Cl2 C 2/m 2/m

Other Ecdemite Information

References:

NAME( Dana8) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Enc. of Minerals,2nd ed.,1990)

See Also:

Links to other databases for Ecdemite :
1 -Am. Min. Crystal Structure Database 2 -Athena 3 - EUROmin Project 4 -Google Images 5 -Google Scholar 6 -Handbook of Mineralogy (UofA) 7 -MinDAT 8 -MinMax(Deutsch) 9 -MinMax(English) 10 -Mineralienatlas (Deutsch) 11 -QUT Mineral Atlas 12 -École des Mines de Paris

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Ecdemite

Pb6As+++2O7Cl4
Dana No: 46.2.1.1 Strunz No: III/D.11-110
Locality:

Notes: