In 2006 Weatherington-Rice and Bigham (paper attached) reported the presence of green-rust, a mixed FeII/FeIII valence mineral in pre-Illinoian lacustrine deposits in Clermont County, OH. The mineral exhibits bright green or blue colors that are off the charts used by soil scientists and geologist to describe color (hue and value of gleyed colors but higher chromas ranging to turquoise--10BG 3/6 to 5/6). The mineral is unstable when exposed to oxygen and quickly reverts to more typical soil colors. The only other natural occurrence of green rust that I am aware of is Fougerite found in forested hydromorphic soils formed in Saprolite in Brittany, France.
Ongoing work by the Indiana Geological and Water Survey in the area of Glacial Lake Patoka in southwestern Indiana has found many references in well driller logs to presumed pre-Illinoian fine-grained sediments with green or blue color that are hypothesized to indicate green rust.
Has anyone else encountered something like this in the field?
‘morning Russel,
The blue/green colour is that of iron in it’s reduced Fe II state and this is a clear indicator for an alkaline anoxic soil.
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