Thermal magnetic susceptibility data on natural iron sulfidesof northeastern Russiaстатья
Информация о цитировании статьи получена из
Web of Science,
Scopus
Статья опубликована в журнале из списка Web of Science и/или Scopus
Дата последнего поиска статьи во внешних источниках: 11 декабря 2016 г.
Аннотация:Dependences of magnetic susceptibility (MS) on the temperature of natural iron sulfide samples (pyrite, marcasite, greigite, chalcopyrite,
arsenopyrite, pyrrhotite) from the deposits of northeastern Russia were studied. The thermal MS curves for pyrite and marcasite are the same:
On heating, MS increases at 420–450 ºC, and unstable magnetite (maghemite) and monoclinic pyrrhotite with a well-defined Hopkinson peak
are produced. In oxygen-free media with carbon or nitrogen, magnetite formation is weak, whereas pyrrhotite generation is more significant.
The heating curves for chalcopyrite are similar to those for pyrite. They show an increase in MS at the same temperatures (420–450 ºC).
However, stable magnetite is produced, whereas monoclinic pyrrhotite is absent. In contrast to that in pyrite, marcasite, and chalcopyrite,
magnetite formation in arsenopyrite begins at >500 ºC. Arsenopyrite cooling is accompanied by the formation of magnetite (S-rich arsenopyrite)
or maghemite (As-rich arsenopyrite) with a dramatic increase in MS. Arsenopyrite with an increased S content is characterized by insignificant
pyrrhotite formation. Greigite is marked by a decrease in MS on the heating curves at 360–420 ºC with the formation of unstable cation-deficient
magnetite.
Monoclinic pyrrhotite is characterized by a decrease in MS at ~320 ºC, and hexagonal pyrrhotite, by a transition to a ferrimagnetic state
at 210–260 ºC. The addition of organic matter to monoclinic pyrrhotite stimulates the formation of hexagonal pyrrhotite, which transforms
back into monoclinic pyrrhotite on repeated heating. The oxidation products of sulfides (greigite, chalcopyrite) show an increase in MS at
240–250 ºC owing to lepidocrocite