A convenient method for measuring ferric iron in magnesiowu¨ stite (MgO-Fe1-xO)

We present a new oxybarometer for magnesiowüstite-bearing systems, which is easily applied using widely available techniques. A scale relating the proportion of Fe [α = Fe /(Fe + Fe )] to the position of the (220) reflection and total Fe (y) in magnesiowüstites (Mg -y · Fe O has been derived from me...

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Bibliographic Details
Published in:The American mineralogist 1998-07, Vol.83 (7), p.794-798
Main Authors: Dobson, David P., Cohen, Neil S., Pankhurst, Quentin A., Brodholt, John P.
Format: Article
Language:English
Online Access:Get full text
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Summary:We present a new oxybarometer for magnesiowüstite-bearing systems, which is easily applied using widely available techniques. A scale relating the proportion of Fe [α = Fe /(Fe + Fe )] to the position of the (220) reflection and total Fe (y) in magnesiowüstites (Mg -y · Fe O has been derived from measured values in samples equilibrated at various oxygen fugacities: α = 13.0047 - 39.4829f + 40.0540f - 13.5701f (±0.007 + 0.09α), f = (d - 1.4890)/(0.0510y + 0.0206y )(±0.0001). Previously established partition coefficients can then be used to relate estimated Fe content to equilibrium oxygen fugacity (f ) in the composition range 0 < y < 0.2. Equi­librium oxygen fugacities of log f ≤ -1.7 can be estimated to ±0.5 log units using just X-ray powder diffraction and electron microprobe analytical techniques.
ISSN:0003-004X
1945-3027
DOI:10.2138/am-1998-7-811