Abstract:

Magnetiteandhematitearethetwoformsofironoxidesinnaturalenvironment,andalsothemainoremineralsofthe GongchanglingirondepositinLiaoningprovince,NorthChina.Inthepast,itisgenerallyacceptedthatredoxreactionistheonly processfortheconversionbetweenmagnetiteandhematite.Recently,non-redoxreactiontheorypresentedanalternativetransformation relationshipbetweenmagnetiteandhematitefortheGongchanglingirondeposit.Inthisstudy,withthepolarizationmicroscopeandthe scanningelectronmicroscopybackscattering(BSE)analysis,thestructurecharacteristicsoftheoresamplesfromthedepositwere analyzed,includingthemetasomatismfrommagnetitetohematite,thereplacementofhematitetogoethite,andtheparagenesisamong pyrite,magnetiteandhematite.Throughcharacterizationofmineralassemblages,thestructurecharacteristicsofores,thevolume change of the iron oxides before and after the transformation, we suggest that part of epigenetic hematite which exists in the Gongchanglingirondepositmaybetransformedintheanoxicandreducingenvironmentfrommagnetitethroughthenon-oxidation reaction.Thisprovidesanewexplanationfortheformationmechanismoftheepigenetichematiteinthisirondeposit.

Key words: Gongchanglingirondeposit;magnetite;hematite;redoxreaction;non-redoxreaction