People at Fort Hoofddijk

Cor de Boer
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Dr. C.B. de Boer
PhD 1994-1999
Now at:
Technologiestichting STW
Van Vollenhovenlaan 661
3527 JP Utrecht
Phone:  +31 30 600 1211
E-mail: Cor@stw.nl

Research
Publications



Research of Cor de Boer

Magnetic properties of maghemite and hematite
Fundamental rock magnetic requires studying the magnetic properties of natural and synthetic magnetic minerals as function of chemical composition, crystallinity and grain size. 
This research determined diagnostic rock magnetic parameters of hematite and maghemite. These magnetic ferric oxides are common in a wide variety of rock types and soils. Hence, their importance for paleomagnetism, soil- and environmental sciences and paleoclimate reconstructions is evident. 
Hematite  (a-Fe2O3 )
This most stable iron oxide is named after the Greek word haimatitis (blood red), in allusion to its colour. The magnetic properties of hematite appear to be extremely variable and are susceptible to the distorting effect of minute amounts of magnetic contaminants.

Hematite is referred to as canted antiferromagnetic. De Boer and Dekkers (1998) measured the thermomagnetic behaviour of a pure and defect-poor hematite.

blades of hematite a nice big chunk of solid hematite
Maghemite  ( g-Fe2O3 )
The name of this highly magnetic iron oxide is formed from the first syllables of magnetite (Fe3O4) and hematite. It has the same chemical composition as hematite, but its structure is similar to magnetite. In nature, maghemite is predominantly formed by low-temperature oxidation of magnetite. It is, however, thermodynamically metastable and inverts to hematite on heating above ~250 °C. Average hysteresis properties resemble those of magnetite, but De Boer and Dekkers (1996) found small but significant differences. 

Fortunately, this dungeon has a window ...
For 4 years, you are trapped in the dungeons of the Fort

With the International Institute for Aerospace Survey and Earth Sciences (ITC) we were involved in the research and the fight against the subsurface coal fires in China by dating the paleo-coal fires magnetostratigraphically. 

Shaking hands ...

Coal fires in China

publicationsPublications of Cor de Boer
2004
  • Zangh, X. Kroonenberg, S.B. and de Boer, C.B. (2004). Dating of coal fires in Xinjiang, north-west China, Terra Nova, 16, 68-74. 
2001
  • De Boer, C.B. and Dekkers, M.J. (2001). Unusual thermomagnetic behaviour of haematites: neoformation of a highly magnetic spinel phase on heating in air.  Geophys. J. Int., 144, 481-494.
  • De Boer, C.B., Mullender, T.A.T. and Dekkers, M.J. (2001). Low-temperature behaviour of haematite: susceptibility and magnetization increase on cycling through the Morin transition, Geophys. J. Int., 146, 201-216. 
  • De Boer, C.B., Dekkers, M.J. and Van Hoof, A.A.M. (2001). Rock magnetic properties of TRM carrying baked and molten rocks straddling burnt coal seams, Phys. Earth Planet. Inter., 126, 93-108 
2000
  • Vlag, P., Alva-Valdivia, L., de Boer, C.B., Gonzalez, S. and Urrutia-Fucugauchi, J. (2000). A rock- and paleomagnetic study of a Holocene lava flow in Central Mexico, Phys. Earth Planet. Inter., 118, 259-272. 
1999
  • De Boer, C.B. (1999). Rock-Magnetic studies on Hematite, Maghemite and Combustion-Metamorphic Rocks (PhD thesis, Utrecht University), Geologica Ultraiectina, 177, 254 pp.
1998
  • De Boer, C. and Dekkers, M.J. (1998). Thermomagnetic behaviour of haematite and goethite as a function of grain size in various non-saturating magnetic fields. Geophys. J. Int., 133, 541-552.
1996
  • De Boer, C.B. and Dekkers, M.J. (1996). Grain-size dependence of the rock magnetic properties for a natural maghemite, Geophys. Res. Lett.,23, 2815-2818.
  • Petrovsky, E., Kropacek, V. Dekkers, M.J., de Boer, C., Hoffman, V. and Ambatiello, A. (1996). Transformation of hematite to maghemite as observed by changes in magnetic parameters: Effects of mechanical activation ?, Geophys. Res. Lett., 23, 1477-1480.