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A comparison of iron extraction methods for the determination of degree of pyritisation and the recognition of iron-limited pyrite formationMeasurements of degree of pyritisation require an estimate of sediment iron which is capable of reaction with dissolved sulphide to form pyrite, either directly or indirectly via iron monosulphide precursors. Three dissolution techniques (buffered dithionite, cold 1 M HCl, boiling 12 M HCl) were examined for their capacity to extract iron from a variety of iron minerals, and iron-bearing sediments, as a function of different extraction times and different grain sizes. All the iron oxides studied are quantitatively extracted by dithionite and boiling HCl (but not by cold HCl). Both HCl techniques extract more iron from silicates than does dithionite but probably about the same amounts as are potentially capable of sulphidation. Modern sediment studies indicate that most sedimentary pyrite is formed rapidly from iron oxides, with smaller amounts formed more slowly from iron silicates (if sufficient geologic time is available). It is therefore recommended that the degree of pyritisation be defined with respect to the dithionite-extractable (mainly iron oxide) pool and/or the boiling HCl-extractable pool (which includes some silicate iron) for the recognition of iron-limited pyritisation.
Document ID
20040089539
Acquisition Source
Headquarters
Document Type
Reprint (Version printed in journal)
Authors
Raiswell, R.
(Leeds University United Kingdom)
Canfield, D. E.
Berner, R. A.
Date Acquired
August 21, 2013
Publication Date
January 1, 1994
Publication Information
Publication: Chemical geology
Volume: 111
ISSN: 0009-2541
Subject Category
Exobiology
Funding Number(s)
CONTRACT_GRANT: OCE 8822977
CONTRACT_GRANT: NAGW-3117
Distribution Limits
Public
Copyright
Other
Keywords
NASA Discipline Exobiology
Non-NASA Center

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