USGS OFR 03-346
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Figure 5

Figure 5a. Picture of typical iron-bearing ground water emerging as a spring. The iron is oxidized to ferric hydroxide upon encountering the oxic environment of the surface. A large number of these springs and seeps on the flood plain provide the iron for bog iron deposits.

Figure 5b. Samples of "bog ore" from Nassawango Creek show vugs lined with goethite around massive "ochre".

Figure 5c. Transmitted light photo-micrograph is about 0.5cm on the vertical axis. Black areas of goethite may include magnetite that has been identified by X-ray diffraction of powdered ore. Light areas may be vugs or stained quartz.