Modderite Mineral Data

Modderite Mineral Data +

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General Modderite Information

Chemical Formula:

(Co,Fe)As

Composition:

Molecular Weight = 133.08 gm

Iron 10.49 % Fe

Cobalt 33.21 % Co

Arsenic 56.30 % As

______

100.00 %

Empirical Formula:

Co_0.75Fe²⁺_0.25As

Environment:

In heavy mineral concentrates.

IMA Status:

Valid Species (Pre-IMA) 1924

Locality:

Modderfontein mine, Witwatersrand, Transvaal, South Africa. Link to MinDat.org Location Data.

Name Origin:

Named for the locality.

Synonym:

ICSD 48026

PDF Sep-94

Modderite Image

Images:

Modderite

Comments: Synthetic crystal of modderite grown for study of this extremely rare mineral.
Location: None, grown in a laboratory. Scale: Grain size 100 µ-m.
© Katie Phillips / Vassar College

Modderite Crystallography

Axial Ratios:

a:b:c =0.5891:1:0.9016

Cell Dimensions:

a = 3.458, b = 5.869, c = 5.292, Z = 4; V = 107.40 Den(Calc)= 8.23

Crystal System:

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

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

By Intensity(I/I_o): 12.1(1), 2.46(0.9), 4.48(0.8),

Crystal Structure:

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Lyman P S , Prewitt C T , Acta Crystallographica, Section B , 40 (1984) p.14-20, Room- and high-pressure crystal chemistry of CoAs and FeAs, Locality: synthetic, Note: anisoB s taken from ICSD, Sample: Pnam refinement, P = .0001 GPa

View Additional jPOWD Structure files for Modderite
[1] [2] [3] [4] [5]

Physical Properties of Modderite

Color:

Bluish white, Steel gray.

Diaphaniety:

Opaque

Habit:

Granular - Generally occurs as anhedral to subhedral crystals in matrix.

Habit:

Microscopic Crystals - Crystals visible only with microscopes.

Hardness:

4 - Fluorite

Luster:

Metallic

Streak:

gray

Calculated Properties of Modderite

Electron Density:

r_electron=7.39 gm/cc
note: r_Modderite=8.23 gm/cc.

Fermion Index

Fermion Index = 0.00222
Boson Index = 0.99778

Photoelectric:

PE_Modderite= 55.86 barns/electron
U=PE_Modderite x r_electron= 412.81 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Modderite is Not Radioactive

Modderite Classification

Dana Class:

2.8.18.1 (2)Sulfides - Including Selenides and Tellurides

(2.8)where Am Bn Xp, with (m+n):p=1:1

(2.8.18)Dana Group

2.8.18.1 Modderite (Co,Fe)As Pmcn 2/m 2/m 2/m

Strunz Class:

II/C.19-40 II - Sulfides and sulphosalts

II/C - Sulfides with metal: sulfur, selenium and tellurium = 1:1

II/C.19 - Troilite - Pyrrhotite - Haideite series

II/C.19-10 Troilite FeS P 6₃/mmc 6/m 2/m 2/m

II/C.19-20 Pyrrhotite Fe(1-x)S(x=0-0.17) A2/a 2/m

II/C.19-25 Jaipurite* CoS P 6₃/mmc 6/m 2/m 2/m

II/C.19-30 Westerveldite (Fe,Ni,Co)As Pnam 2/m 2/m 2/m

II/C.19-40 Modderite (Co,Fe)As Pmcn 2/m 2/m 2/m

II/C.19-50 Smythite (Fe,Ni)9S11or(Fe,Ni)13S16 R 3m 3 2/m

II/C.19-60 Achavalite* FeSe P 6₃/mmc 6/m 2/m 2/m

II/C.19-70 Heideite (Fe,Cr)1x(Ti,Fe)2S4 I2/m 2/m

Other Modderite Information

References:

NAME( AntBidBlaNic1) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990)

See Also:

Links to other databases for Modderite :
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 - WWW-MINCRYST 13 -École des Mines de Paris

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

Modderite

(Co,Fe)As
Dana No: 2.8.18.1 Strunz No: II/C.19-40
Locality:

Notes: