HR: 08:35h
AN: GP31A-03 INVITED     [PDF]
TI: The Other Iron Minerals: Magnetic Properties at Room and Low Temperature
AU: * Hirt, A M
EM: hirt@mag.ig.erdw.ethz.ch
AF: ETH-Zurich, Institute of Geophysics ETH-Hoenggerberg, Zurich, 8093 Switzerland
AB: The magnetic properties of iron oxides and iron sulfides that are carriers of paleomagnetic fields have been well studied. Less is known about the magnetic properties of iron phases that are not common carriers of remanent magnetization, or those that are paramagnetic at room temperature. They include iron (oxy-)hydroxides, iron carbonates, iron phosphates and iron sulfates. Many of these phases are not easily identifiable with traditional X ray diffraction or spectroscopic methods, due to their poor crystallinity or low concentration in soils and sediments. Since they are important indicators of the environmental conditions under which they form and are preserved, alternative methods for their identification are of interest. AC and DC magnetometry are very sensitive in detecting low concentrations of magnetic phases. A short overview will be given on the magnetic properties of less-considered iron phases, including the iron (oxy-)hydroxides goethite, lepidocrocite and ferrihydrite; siderite, an iron carbonate; the iron phosphate vivianite; and iron sulfate, schwertmannite. Factors that influence the magnetic properties, such as cation substitution, grain size and particle interaction will be discussed, as well as the environmental conditions under which they form and are preserved.
DE: 1519 Magnetic mineralogy and petrology
DE: 1540 Rock and mineral magnetism
SC: Geomagnetism and Paleomagnetism [GP]
MN: 2003 Fall Meeting