This prompted inter-
ruption of the experiment at approximately 75 min;
Fig. 3. in order to filter the sample and further
increase sample density. This process, however,
compromised the anoxic nature of the reactants.
After approximately 85 min, the sample was returned
to the beam at 1108C. as a thicker paste and the
presence of greigite and pyrite became clearly visible
under these slightly oxic conditions.