Modderite Mineral Data

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.

Name Pronunciation:

Modderite + Pronunciation

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.

Diaphaneity:

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:

Bulk Density (Electron Density)=7.39 gm/cc
note: Specific Gravity of Modderite =8.23 gm/cc.

Fermion Index:

Fermion Index = 0.0022240898
Boson Index = 0.9977759102

Photoelectric:

PE_Modderite= 55.86 barns/electron
U=PE_Modderite x rElectron Density= 412.81 barns/cc.

Radioactivity:

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

Modderite Classification

Dana Class:

02.08.18.01 (02)Sulfides - Including Selenides and Tellurides

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

(02.08.18)Dana Group

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

Strunz Class:

02.CC.15 02 - SULFIDES and SULFOSALTS (sulfides, selenides, tellurides; arsenides, antimonides, bismuthides; sulfarsenites, sulf

02.C - Metal Sulfides, M:S = 1:1 (and similar)

02.CC -With Ni, Fe, Co, PGE, etc.

02.CC.15 Cherepanovite RhAs P nma 2/m 2/m 2/m

02.CC.15 Modderite (Co,Fe)As Pmcn 2/m 2/m 2/m

02.CC.15 Ruthenarsenite (Ru,Ni)As P nma 2/m 2/m 2/m

02.CC.15 Westerveldite (Fe,Ni,Co)As Pnam 2/m 2/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 - 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
15 - WWW-MINCRYST

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Ask about Modderite here :
Ask-A-Mineralogist from the Mineralogical Society of America
Mindat.org's Discussion Groups
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Mineral Discussion Forum from Fabre Minerals - also available in Español

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

Modderite

(Co,Fe)As
Dana No: 02.08.18.01 Strunz No: 02.CC.15
Locality:

Notes: