Electronic Resource
Springer
Contributions to mineralogy and petrology
78 (1982), S. 352-357
ISSN:
1432-0967
Source:
Springer Online Journal Archives 1860-2000
Topics:
Geosciences
Notes:
Abstract The relationship between the redox ratio Fe+2/(Fe+2+Fe+3) and the K2O/(K2O + Al2O3) ratio (K2O*) were experimentally investigated in silicate melts with 78 mol% SiO2 in the system SiO2-Al2O3-K2O-FeO-Fe2O3, in air at 1,400° C. Quenched glass compositions were analyzed by electron microprobe and wet chemical microtitration techniques. Minimum values of the redox ratio were obtained at K2O*≈0.5. The redox ratio in peralkaline melts (K2O*〉0.5) increases slightly with K2O* whereas this ratio increases dramatically in peraluminous melts (K2O*〈0.5) as K2O is replaced by Al2O3. These data indicate that all Fe+3 (and Al+3) occur as tetrahedral species charge balanced with K+ in peralkaline melts. In peraluminous melts, Fe+3 (and Al+3) probably occur as both tetrahedral species using Fe+2 as a charge-balancing cation and as network-modifying cations associated with non-bridging oxygen.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00398931
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