Ecdemite Mineral Data

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.

Name Pronunciation:

Ecdemite

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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

Diaphaneity:

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
Ncalc = 2.13 - 2.2

Optical Data:

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

Calculated Properties of Ecdemite

Electron Density:

Bulk Density (Electron Density)=6.06 gm/cc
note: Specific Gravity of Ecdemite =7.32 gm/cc.

Fermion Index:

Fermion Index = 0.16
Boson Index = 0.84

Photoelectric:

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

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)
Ecdemite is Not Radioactive

Ecdemite Classification

Dana Class:

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

(46.02)with miscellaneous formulae

(46.02.01)Dana Group

46.02.01.01 Ecdemite Pb6As2O7Cl4 Unk Tetra

Strunz Class:

03.DC.65 03 - HALIDES

03.D - Oxyhalides, Hydroxyhalides and Related Double Halides

03.DC -With Pb (As,Sb,Bi), without Cu

03.DC.65 Ecdemite Pb6As2O7Cl4 Unk Tetra

03.DC.65 Heliophyllite Pb6As2O7Cl4 Unk Ortho

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 - Ecole des Mines de Paris
5 - GeoScienceWorld
6 - Google Images
7 - Google Scholar
8 - Handbook of Mineralogy (MinSocAm)
9 - Handbook of Mineralogy (UofA)
10 - MinDAT
11 - Mineralienatlas (Deutsch)
12 - Online Mineral Museum
13 - QUT Mineral Atlas
14 - Ruff.Info

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Print or Cut-and-Paste your Ecdemite Specimen Label here :

Ecdemite

Pb6As+++2O7Cl4
Dana No: 46.02.01.01 Strunz No: 03.DC.65
Locality:

Notes: