My guess is lead coffins. Fairly common in 17th and 18th century graves,
especially of fairly wealthy folks.
 
Dan Mouer
Virginia Commonwealth University
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http://saturn.vcu.edu/~dmouer/homepage.htm
 
On Thu, 26 Mar 1998, David Breetzke wrote:
 
>         During excavations at a Baptist church graveyard (the
> congregation is interested in finding the remains of a 17th
> century church structure),active from 1770-1890, dozens of small
> chunks of lead were recovered from the plowzone (graves were not
> disturbed).   The site location is Middletown, New Jersey.   Any idea
> what, if any, use they may have had?  Thank you in advance for any
> info!
>
> Gerry Scharfenberger
>