Maghemite Mineral Data

Maghemite Mineral Data +

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General Maghemite Information

Chemical Formula:

gamma-Fe+++2O3

Composition:

Molecular Weight = 159.69 gm

Iron 69.94 % Fe 100.00 % Fe₂O₃

Oxygen 30.06 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

Fe³⁺₂O₃

Environment:

Formed by weathering or low-temperature oxidation of spinels containing ferrous iron, commonly magnetite or titanian magnetite. Widespread yellow pigment in sediments.

IMA Status:

Valid Species (Pre-IMA) 1927

Locality:

Iron mountain mine, 9.5 miles NW of Redding, Shasta Co., California. Link to MinDat.org Location Data.

Name Origin:

From MAGnetite and HEMatite, in allusion to the mineral's magnetism and composition.

Maghemite Image

Images:

Maghemite

Comments: Fine-grained massive maghemite intermixed with hematite.
Location: Gara Djebilet, Algeria. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Maghemite Crystallography

Cell Dimensions:

a = 8.339, Z = 12; V = 579.89 Den(Calc)= 5.49

Crystal System:

Isometric - TetartoidalH-M Symbol (2 3) Space Group: P 2₁3

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

By Intensity(I/I_o): 1.61(1), 2.52(1), 2.95(1),

Crystal Structure:

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Pecharroman C , Gonzalez-Carreno T , Iglesias J E , Physics and Chemistry of Minerals , 22 (1995) p.21-29, The infrared dielectric properties of maghemite, gamma-Fe2O3,, from reflectance measurement on pressed powders, Sample: c) idealized, either one of Fe-oct 1-6,, or both Fe-oct 6-7 have zero occupancy

Physical Properties of Maghemite

Cleavage:

None

Color:

Dark brown.

Density:

4.9

Diaphaniety:

Opaque

Fracture:

Sub Conchoidal - Fractures developed in brittle materials characterized by semi-curving surfaces.

Habit:

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

Habit:

Massive - Uniformly indistinguishable crystals forming large masses.

Hardness:

6 - Orthoclase

Luster:

Metallic

Magnetism:

Strongly magnetic

Streak:

brown

Optical Properties of Maghemite

Optical Data:

Isotropic.

NCalc= 2.73 - from Gladstone-Dale relationship (KC = 0.315) where Ncalc=Dcalc*KC+1
NCalc= 2.54 - from Gladstone-Dale relationship (KC = 0.315) where Ncalc=Dmeas*KC+1

RL Color:

White to bluish gray.

Reflectivity

**Standardized Intensity (100%) Reflection Spectra of Maghemite in Air**
λ	R	∑ R(λ)
400 nm	31.50
420 nm	30.20
440 nm	28.50
460 nm	27.60
480 nm	26.60
500 nm	26.00
520 nm	25.50
540 nm	24.80
560 nm	24.00
580 nm	23.20
600 nm	22.40
620 nm	22.00
640 nm	21.60
660 nm	21.20
680 nm	20.80
700 nm	20.40

**Calculated Relative Intensity Colors of Maghemite in Air**
Relative Intensity	0%	40%	80%	100%	120%	160%	200%	240%	280%	320%	360%	390%
R

Calculated Properties of Maghemite

Electron Density:

r_electron=5.23 gm/cc
note: r_Maghemite=5.49 gm/cc.

Fermion Index

Fermion Index = 0.01497
Boson Index = 0.98503

Photoelectric:

PE_Maghemite= 21.37 barns/electron
U=PE_Maghemite x r_electron= 111.70 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Maghemite is Not Radioactive

Maghemite Classification

Dana Class:

4.3.7.1 (4)Simple Oxides

(4.3)with a cation charge of 3+ (A+++2 O3)

(4.3.7)Dana Group

4.3.7.1 Maghemite gamma-Fe2O3 P 2₁3 2 3

4.3.7.2 Bixbyite (Mn,Fe)2O3 I a3 2/m 3

Strunz Class:

IV/C.06-10 IV - Oxides

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

IV/C.06 - Ilmenite group, Maghemite series

IV/C.06-10 Maghemite gamma-Fe2O3 P 2₁3 2 3

Other Maghemite Information

References:

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

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Maghemite

gamma-Fe+++2O3
Dana No: 4.3.7.1 Strunz No: IV/C.06-10
Locality:

Notes: