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Techniques for CollectorsFeOtot recalculation to FeO and Fe2O3 by stoichiometry

16th Mar 2011 08:38 UTCŁukasz Kruszewski Expert

Hello everyone!

Would like to ask if you know about a "universal" method to recalculate FeOtot to FeO and Fe2O3 by stoichiometry? I know about a method of Carmichael, i.e. recalculation on ulvospinel and ilmenite basis, but it seems to be only for spinels (please correct me if I'm wrong).

Is there a formula for such recalculation for any mineral?

Best regards,

Luke

16th Mar 2011 13:24 UTCJohan Kjellman Expert

I calculate formulas in xcel-spreadsheats. I then put analysed Fe expressed as FeO* in one column. Then I have one cell for FeO (which is the value I play with) and one for Fe2O3.

Then "calculating" FeO and Fe2O3 is done the following way:

First your mineral must have some constraining conditions, i.e. total number of oxygens or cations, etc. which you have as a formula in one of the cells.

Then in the Fe2o3 cell you put the formula

(FeO*-FeO) x 1,11138

In the FeO-cell you now assign a value and check your "constraining condition cell" and adjust until it has the right value.

cheers

16th Mar 2011 14:26 UTCAlfredo Petrov Manager

If you are starting with microprobe data, Lukasz, there isn't any one method that will work for all minerals. In some cases you won't know O:OH, for example, so you won't be able to calculate it at all by stoichiometry.

16th Mar 2011 19:18 UTCŁukasz Kruszewski Expert

Thank you very much, Sirs! (-:

16th Mar 2011 23:44 UTCRalph S Bottrill 🌟 Manager

Its simple enough for many anhydrous minerals as per Johan, but minerals with vacancies or OH and undetermined elements can be impossible. Schumacher (1997) came up with a method for amphiboles, but it does not always give a good result (Can Min v35 p237-246).

17th Mar 2011 08:21 UTCŁukasz Kruszewski Expert

Thank you, Ralph! Its all indeed not that simple..

Cheers!

Luke

21st Jun 2012 16:44 UTCEgbo Akpesiri

We work with mineral(zircon sand) with Fe2O3:1.86% how do i calculate the separation of FeO from Fe2O3.what value will it give me?The report of the material is attached.

Best regards,

Egbo

21st Jun 2012 17:16 UTCAlfredo Petrov Manager

Egbo, Unfortunately this is not possible without knowing the mineralogical purity of the zircon sand itself; in other words, what mineral is the Fe³⁺ present in?

26th Jul 2012 19:01 UTCShah Alam

I have been done Geochemistry of Sedimentary deposit/Red soil and found Fe2O3: 8.56%, how do I calculate the separation of FeO wt% from Fe2O3 wt%.

31st Aug 2012 23:52 UTCRalph S Bottrill 🌟 Manager

To determine the FeO/Fe2O3 contents there are standard wet chemical methods, based on the dissolution of the soil and titration to determine FeO, then determine Fe2O3 by difference from the total Fe.

11th Jan 2014 14:25 UTCBISHADY

CAN I GET A METHOD TO CALCULATE THE FeO/Fe2O3 RATIO FROM THE Fe2O3 MICROPROBE ANALYSISFOR BIOTITE

THANK YOU IN ADVANCE

A.M. BISHADY

CAIRO, EGYPT

12th Jan 2014 03:54 UTCJohn Attard Expert

A wet chemical analysis I know involves dissolving a known weight of the dry mineral powder in suitable acids under conditions that exclude oxygen, dilute suitably and titrate with standard permanganate to get the Iron2. If you then pass the resulting solution or an aliquot of the stock solution, through a Jones Reductor (amalgamated zinc in a burette-like tube) the Iron will end up being reduced to Iron2.

One then titrates with permanganate again to get the total iron.

Is that what you were looking for?

John Attard, San Diego, California.

12th Jan 2014 17:12 UTCHassan tharwat

the geochemical data of my work includes only Fe2O3 , i want to get FeOtot from it

then calculating FeOtot/MgO ratio.

i need your help please

thanks

12th Jan 2014 23:32 UTCEmil Box

Hi Hassan,

the factor to calculate FeO from Fe₂O₃ is 0.8998

Milo

13th Jan 2014 11:25 UTCZbynek Burival Expert

There is no general way to recalculate Fe2+ and Fe3+. It is too difficult in many silicates. There are undetermined other elements, vacancies, uncertain water/OH content, more elements with different oxidation state etc. Sometimes you can use "brute force" - like calculating garnet on 12 anions and 8 cations with valence calculation - but of course results of this may be quite far from reality.

The wet analysis is impossible for mixed, altered or too small minerals. You may avoid undetermined elements by using LA-ICP-MS, sometimes just this helps to get the formula. Sometimes the structure can help, eg. if you can say there is no Fe in position typical for Fe3+ - Raman and IR spectroscopy or xray diffraction help with this. The most efficient method is to use Mossbauer spectroscopy which can directly analyse and distinguish Fe2+ and Fe3+.

To get FeO to Fe2O3 just multiply FeO by 1,11111... Fe2O3 to FeO is just reverse, divide Fe2O3 by 1,11111 (or multiply by 0,899999 as said above).

21st Jan 2014 09:31 UTCMaarten VU

Zbynek Burival Wrote:

-------------------------------------------------------

>

> To get FeO to Fe2O3 just multiply FeO by

> 1,11111... Fe2O3 to FeO is just reverse, divide

> Fe2O3 by 1,11111 (or multiply by 0,899999 as said

> above).

What is the calculation behind this? Where does the number 1,1111 come from?

I have my XRF analysis in Fe2O3, but my modelling program only accepts FeO. So I would like to know how the 1,1111 is calculated.

21st Jan 2014 12:33 UTCJohan Kjellman Expert

it is the ratio of the molecular weight of half a molecule of Fe2O3 and one molecule of FeO

cheers

14th Sep 2014 10:10 UTCDeva Ram

Dear sir how to calculate FeO and Fe2O3 and FeO Total from analysed Fe2O3 total by XRF.

2nd Nov 2015 17:54 UTCMuha

Hello

Could you help me to calculate the FeO and Fe2O3 from total iron composition in the total rock, please.

Best regards

30th Oct 2017 13:42 UTCfaiza debabha

Dear sir how to calculate FeO and Fe2O3 from analysed FeO total by EPMA for minerals

30th Oct 2017 16:04 UTCJohan Kjellman Expert

Dear Faiza,

It depends on what mineral.

please specify and/or give an example of your raw data

cheers

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