Recently, while freediving for hard-shell clams (quohogs) I found a
metal railroad spike with wood still attached.  On close inspection, the
spike is not steel or iron, it appears to be brass, or maybe iron.  It
is covered with black corrosion, and the spots that do not have it are
gold in color.  The wood attached is near the top of the spike, and
appears to be in good condition.  The piece most likely dates back to
the late 19th century, when a railroad bridge was built approx. 100 yard
from the dive site, and has most likely been in the water since 1938,
when a hurricane blew the bridge into the water.  Here are a few
pictures I took of the spike, using my webcam.

This is a picture of the whole thing from above
http://tinyurl.com/2jecm
The next 3 are of teh wood stuck to it
http://tinyurl.com/3fk8n

http://tinyurl.com/ysoyf

http://tinyurl.com/2otug

My question is, what metal does this sound like? How would I go about
preserving this piece with the wood attached? Any information you could
give me, or a link to a resource that would help would be great.  

Thanks in advance!

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