Iron bloom

Ancient iron structures sometimes show no sign of corrosion or at most, very little. The clean atmosphere of past centuries may be responsible in that it allowed a very thin adherent layer of oxide to develop on the surface [22], This layer very often protects against even today s increasingly aggressive industrial pollutants Very often the conditions of the initial corrosion are the ones that determine the lifespan of metals [23], A well-known example is the sacred pillar of Kutub in Delhi, which was hand forged from large iron blooms in 410 a.d. In the pure dry air, the pillar remains free of rust traces but shows pitting corrosion of the iron... 

Sayre, E. V., Harbottle, G., Stoenner, R. W., Washburn, W., Olin, S., Fitzhugh, W., The Carbon 14 Dating of ao Iron Bloom Associated with the Voyages of Sir Martin Frobisher, Chapter 22 in this book. 

The Carbon-14 Dating of an Iron Bloom Associated with the Voyages of Sir Martin Frobisher... 

Development of proportional counters to measure C14/C12 ratios in 10 mg carbon samples was undertaken in the Chemistry Department of Brookhaven National Laboratory in 1975 [10] for two reasons (1) at the time, there was no other possibility in sight to accomplish the generally much-needed objective of small-sample C14 measurement, and (2) there was a particular carbon 14 dating problem at the Smithsonian Institution, which would only be solved if very small carbon samples could be handled. The development and testing of the counters has already been reported [9] in the present paper we discuss the application of those counters to the actual dating problem which concerned the Smithsonian Institution, the dating of the "Frobisher iron bloom". 

Figure 1. An iron bloom in the collection of the Department of Naval History, National Museum of American History, Smithsonian Institution (Cat. No. 49459). The bloom weighs approximately 17 lb, after sampling, and is approximately 18 cm in diameter on the base as shown. (Smithsonian Institution negative No.

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