Cotunnite Mineral Data

Cotunnite Mineral Data

General Cotunnite Information

Chemical Formula:

PbCl2

Composition:

Molecular Weight = 278.11 gm

Lead 74.50 % Pb 80.26 % PbO

Chlorine 25.50 % Cl 25.50 % Cl

- % Cl -5.75 % -O=Cl₂

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

PbCl₂

Environment:

Oxidized lead deposits.

IMA Status:

Valid Species (Pre-IMA) 1825

Locality:

Vesuvius, Italy. Tarapaca, Chile. Link to MinDat.org Location Data.

Synonym:

ICSD 27736

PDF 26-1150

Cotunnite Image

Images:

Cotunnite

Comments: White to tan translucent crystalline cotunnite on volcanic slag.
Location: Vesuvius, Campania, Italy. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Images:

Cotunnite Burnsite

Comments: Images of burnsite grains (dark) in intimate intergrowth with cotunnite (light). Images obtained by scanning electron microscopy.
Location: North Breach of the great fissure Tolbachik volcano eruption (1975-1976), Kamchatka Peninsula, Russia. Scale: Scale bar: 20 µ-m.
© Canadian Mineralogist

Cotunnite Crystallography

Axial Ratios:

a:b:c =0.8427:1:0.5013

Cell Dimensions:

a = 7.6222, b = 9.0448, c = 4.5348, Z = 4; V = 312.63 Den(Calc)= 5.91

Crystal System:

Orthorhombic - DipyramidalH-M Symbol (2/m 2/m 2/m) Space Group: Pnam

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

By Intensity(I/I_o): 3.581(1), 3.89(0.73), 2.778(0.56),

Forms:

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Forms: [ 1 2 0] [ 0 1 0] [ 0 1 1] [ 1 1 1] [ 1 1 0] [ 1 0 0]

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Crystal Structure:

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Wyckoff R W G , Crystal Structures , 1 (1963) p.298-306, Second edition. Interscience Publishers, New York, New York

Physical Properties of Cotunnite

Cleavage:

[001] Perfect

Color:

Colorless, Green, Yellow, White.

Density:

5.3 - 5.8, Average = 5.55

Diaphaniety:

Transparent to translucent

Fracture:

Conchoidal - Uneven - Uneven fracture producing small, conchoidal fragments.

Habit:

Acicular - Occurs as needle-like crystals.

Habit:

Massive - Granular - Common texture observed in granite and other igneous rock.

Hardness:

1.5-2 - Talc-Gypsum

Luster:

Adamantine

Streak:

white

Optical Properties of Cotunnite

Gladstone-Dale:

CI meas= -0.179 (Poor) - where the CI = (1-KPDmeas/KC)
CI calc= -0.107 (Poor) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2073,KPDmeas= 0.2208,KC= 0.1873

Optical Data:

Biaxial (+), a=2.199, b=2.217, g=2.26, bire=0.0610, 2V(Calc)=68, 2V(Meas)=67.2.

Calculated Properties of Cotunnite

Electron Density:

r_electron=4.93 gm/cc
note: r_Cotunnite=5.91 gm/cc.

Fermion Index

Fermion Index = 0.16465
Boson Index = 0.83535

Photoelectric:

PE_Cotunnite=1,372.93 barns/electron
U=PE_Cotunnite x r_electron=6,768.86 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Cotunnite is Not Radioactive

Cotunnite Classification

Dana Class:

9.2.7.1 (9)Anhydrous and Hydrated Halides

(9.2)where A (X)2

(9.2.7)Dana Group

9.2.7.1 Cotunnite PbCl2 Pnam 2/m 2/m 2/m

9.2.7.2 Hydrophilite CaCl2 Pnnm 2/m 2/m 2/m

Strunz Class:

III/D.10-40 III - Halogenides

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

III/D.10 - Cotunnite - Matlockite series

III/D.10-10 Fiedlerite Pb3Cl4F(OH)2 P1 1

III/D.10-20 Paralaurionite PbCl(OH) C 2/m 2/m

III/D.10-30 Laurionite PbCl(OH) Pnam 2/m 2/m 2/m

III/D.10-40 Cotunnite PbCl2 Pnam 2/m 2/m 2/m

III/D.10-50 Pseudocotunnite K2PbCl4(?) P nma 2/m 2/m 2/m

III/D.10-60 Matlockite PbFCl P 4/nmm 4/m 2/m 2/m

III/D.10-65 Rorisite (Ca,Mg)FCl P 4/nmm 4/m 2/m 2/m

III/D.10-70 Zavaritskite BiOF P 4/nmm 4/m 2/m 2/m

III/D.10-80 Bismoclite BiOCl P 4/nmm 4/m 2/m 2/m

III/D.10-90 Daubreeite BiO(OH,Cl) P 4/nmm 4/m 2/m 2/m

III/D.10-140 Symesite! Pb10(SO4)O7Cl4·(H2O) B1 1

Other Cotunnite Information

References:

NAME( Ford32) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Enc. of Minerals,2nd ed.,1990)

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

Cotunnite

PbCl2
Dana No: 9.2.7.1 Strunz No: III/D.10-40
Locality:

Notes: