Buried metal

Jack Ogden <jack [at] striptwist__com> writes

>There are sometimes minute, very fragile meandering tubes on ancient
>buried metal objects that I have always thought of as 'worm casts'
>(though that might not be the right term). ...

I have seen similar tube-like forms on both iron artifacts from
historical sites in the USA and also on bog ores (limonites).

My impression was that these small tubular forms derived their
morphology from organic materials, such as twigs and roots and other
faunal materials, deposited with the artifacts in a
mud/wet/boggy/swamp matrix. This sort of burial environment was
conducive for the formation of a corrosion/soil matrix cast of such
materials, that deteriorate and leave their tubes behind. I have
also seen the impression of small sea shells in such matrices as
well.

I also remember that some of the iron-fixing bacteria in anaerobic
environments leave microscopic tubercle in an iron oxide
crust--remember those famous martian meteoric samples that kicked up
a stir back in the mid-1990's, because there were tubercular forms
of magnetite found in the samples from Antartica?

I hope these possibilities offer some avenues for further
investigation.

David Harvey
Conservator
Griswold Conservation Associates
Beverly Hills, California  USA


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                  Conservation DistList Instance 18:8
                 Distributed: Wednesday, July 21, 2004
                        Message Id: cdl-18-8-003
                                  ***