Ge 214 Homework: 

Available:     12-May-2011.  

Due Wed 18-May-2011.


This problem is to demonstrate how easy it is to use Mössbauer spectra to determine oxidation states of iron in non-complex spectra.  In practice, sophisticated curve-fitting programs are used to interpret such data. However, first-order interpretation can be rapidly made by eye-inspection in many instances.

Four Mössbauer spectra are part of this homework.


The data for each spectrum are presented as:
mm/sec shift relative to metallic iron, Percent Absorption of the gamma rays.

For each mineral,
    a) Graph the Mössbauer spectrum.

    b) Determine what is the dominant oxidation state of iron in this mineral.

    c) Estimate what is the Fe2+ / Fe3+ ratio in this mineral.  (While I don’t expect you to conduct an exact fit, it would be nice if you were able to do this).


1) Here is a Mössbauer data set taken on a diopside that you will need to graph. 


diopside

photo credit: Rob Lavinsky, Irocks.com



2) Next is the Mössbauer data set taken on a tourmaline

tourmaline

photo credit: Rob Lavinsky, Irocks.com

        

 

3) Next is the Mössbauer data set taken on chlorite.
 chlorite group
photo credit: John Betts, Fine Minerals.

 

4) Finally, Roemerite is an example of a mixed oxidation state mineral.

Look at the Mössbauer spectrum of roemerite at:

http://www.mtholyoke.edu/courses/mdyar/database/index.shtml?group=sulf&species=rr8

and perform a quantitative analysis of the oxidation states of Fe in this mineral and the relative proportions of each. You will have to either curve fit, cut & weigh, or do some other clever thing to get quantitative numbers. Does your oxidation state answer agree with the iron oxidation state proprtions in the ideal formula for this mineral?

 

roemerite image

Roemerite, Dexter #7, San Rafael Swell, Utah