Armalcolite Mineral Data

Armalcolite Mineral Data +

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General Armalcolite Information

Chemical Formula:

(Mg,Fe++)Ti2O5

Composition:

Molecular Weight = 207.95 gm

Magnesium 8.77 % Mg 14.54 % MgO

Titanium 46.05 % Ti 76.83 % TiO₂

Iron 6.71 % Fe 8.64 % FeO

Oxygen 38.47 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

Mg_0.75Fe²⁺_0.25Ti₂O₅

Environment:

Ti oxides associated with deep-seated intrusives.

IMA Status:

Approved IMA 1970

Locality:

Tranquillity Base, Moon. Smoky Butte, Garfield Co., MT, Link to MinDat.org Location Data.

Name Origin:

Named after the three astronauts of Apollo 11: Neil A. ARMstrong, Edwin E. "Buzz" ALdrin, and Michael COLlins.

Synonym:

ICSD 15845

Kennedyite-Discredited IMA 1988

PDF 41-1444

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Armalcolite Crystallography

Axial Ratios:

a:b:c =0.9786:1:0.3745

Cell Dimensions:

a = 9.77, b = 9.983, c = 3.739, Z = 4; V = 364.68 Den(Calc)= 3.79

Crystal System:

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

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

By Intensity(I/I_o): 3.468(1), 1.958(0.8), 2.763(0.25),

Crystal Structure:

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Wechsler B A , American Mineralogist , 62 (1977) p.913-920, Cation distribution and high-temperature crystal chemistry of armalcolite, sample Arm-E, T = 24 deg C, before annealing

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

Physical Properties of Armalcolite

Color:

Gray.

Density:

Diaphaniety:

Opaque

Habit:

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

Hardness:

6 - Orthoclase

Luster:

Metallic

Optical Properties of Armalcolite

Optical Data:

Biaxial (?)

NCalc= 2.32 - from Gladstone-Dale relationship (KC = 0.3472) where Ncalc=Dcalc*KC+1
NCalc= 2.39 - from Gladstone-Dale relationship (KC = 0.3472) where Ncalc=Dmeas*KC+1

RL Anisotrophism:

Strong, pale gray to dark bluish gray.

RL Color:

Gray to tan.

RL Pleochroism:

Observed.

Reflectivity

**Standardized Intensity (100%) Reflection Spectra of Armalcolite in Air**
λ	R₁	R₂	∑ R₁(λ)	∑ R₂(λ)
450 nm	14.10	15.20
470 nm	14.00	15.00
500 nm	13.80	14.70
520 nm	13.70	14.50
546 nm	13.40	14.40
586 nm	13.30	14.30
620 nm	13.20	14.20
640 nm	13.00	14.10

**Calculated Relative Intensity Colors of Armalcolite in Air**
Relative Intensity	0%	70%	100%	140%	210%	280%	350%	420%	490%	560%	630%	670%
R₁
R₂

Calculated Properties of Armalcolite

Electron Density:

r_electron=3.63 gm/cc
note: r_Armalcolite=3.79 gm/cc.

Fermion Index

Fermion Index = 0.06991
Boson Index = 0.93009

Photoelectric:

PE_Armalcolite= 9.90 barns/electron
U=PE_Armalcolite x r_electron= 35.91 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Armalcolite is Not Radioactive

Armalcolite Classification

Dana Class:

7.7.1.2 (7)Multiple Oxides

(7.7)with miscellaneous formulae

(7.7.1)Dana Group

7.7.1.1 Pseudobrookite (Fe,Fe)2(Ti,Fe)O5 Bbmm 2/m 2/m 2/m

7.7.1.2 Armalcolite (Mg,Fe)Ti2O5 Bbmm 2/m 2/m 2/m

7.7.1.3 IMA2000-016! (Ti,Fe,Mg,Mn)1-xTi2O5 Pban 2/m 2/m 2/m

Strunz Class:

IV/C.24-10 IV - Oxides

IV/C - Oxides with metal : oxygen = 2:3 (M2O3 and related compounds)

IV/C.24 - Aramcolite - Arizonite series

IV/C.24-10 Armalcolite (Mg,Fe)Ti2O5 Bbmm 2/m 2/m 2/m

IV/C.24-20 Pseudobrookite (Fe,Fe)2(Ti,Fe)O5 Bbmm 2/m 2/m 2/m

IV/C.24-30 Pseudorutile Fe2Ti3O9 P 3₂2 3 2

Other Armalcolite Information

References:

NAME( Dana8) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(AntBidBlaNic3)

See Also:

Links to other databases for Armalcolite :
1 - Am. Min. Crystal Structure Database
2 - Athena
3 - EUROmin Project
4 - Ecole des Mines de Paris
5 - Google Images
6 - Google Scholar
7 - Handbook of Mineralogy (MinSocAm)
8 - Handbook of Mineralogy (UofA)
9 - MinDAT
10 - MinMax(Deutsch)
11 - MinMax(English)
12 - Mineralienatlas (Deutsch)
13 - QUT Mineral Atlas
14 - Ruff.Info
15 - University of Colorado - Mineral Structure Data
16 - WWW-MINCRYST

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Armalcolite

(Mg,Fe++)Ti2O5
Dana No: 7.7.1.2 Strunz No: IV/C.24-10
Locality:

Notes: