Common accessory mineral in igneous and metamorphic rocks. Can be biogenically produced by a wide variety of organisms.
IMA Status:
Valid Species (Pre-IMA) 1845
Locality:
Many localities and environments world wide. Link to MinDat.org Location Data.
Name Origin:
Named for Magnes, a Geek shepherd, who discovered the mineral on Mt, Ida, He noted that the nails of his shoe and the iron ferrule of his staff clung to a rock.
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Physical Properties of Magnetite
Cleavage:
None
Color:
Grayish black, Iron black.
Density:
5.1 - 5.2, Average = 5.15
Diaphaneity:
Opaque
Fracture:
Sub Conchoidal - Fractures developed in brittle materials characterized by semi-curving surfaces.
Habit:
Crystalline - Fine - Occurs as well-formed fine sized crystals.
Habit:
Massive - Granular - Common texture observed in granite and other igneous rock.
Habit:
Massive - Uniformly indistinguishable crystals forming large masses.
Hardness:
5.5-6 - Knife Blade-Orthoclase
Luminescence:
Non-fluorescent.
Luster:
Metallic
Magnetism:
Naturally strong
Streak:
black
Optical Properties of Magnetite
Gladstone-Dale:
CI meas= 0 (Superior) - where the CI = (1-KPDmeas/KC) CI calc= 0.011 (Superior) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2726,KPDmeas= 0.2757,KC= 0.2756 Ncalc = 2.41 - 2.44
Optical Data:
Isotropic, n=2.42.
RL Color:
Gray with brownish tint.
Reflectivity
Standardized Intensity (100%) Reflection Spectra of Magnetite in Air
λ
R
∑ R(λ)
400 nm
22.30
420 nm
21.80
440 nm
21.30
460 nm
20.80
480 nm
20.50
500 nm
20.30
520 nm
20.30
540 nm
20.40
560 nm
20.50
580 nm
20.60
600 nm
20.60
620 nm
20.70
640 nm
20.80
660 nm
20.90
680 nm
21.00
700 nm
21.20
Calculated Relative Intensity Colors of Magnetite in Air
Relative Intensity
0%
50%
100%
150%
200%
250%
300%
350%
400%
430%
R
Calculated Properties of Magnetite
Electron Density:
Bulk Density (Electron Density)=4.89 gm/cc note: Specific Gravity of Magnetite =5.15 gm/cc.
Fermion Index:
Fermion Index = 0.01 Boson Index = 0.99
Photoelectric:
PEMagnetite = 22.14 barns/electron U=PEMagnetite x rElectron Density= 108.32 barns/cc.
Radioactivity:
GRapi = 0 (Gamma Ray American Petroleum Institute Units) Magnetite is Not Radioactive
Chemical Formula: 
