Finally an answer! Thanks Larry and others. A few years ago I found a
small (approx. 1 cm. sq.) "polished" sherd of 18th-c. underglazed
porcelain lying benath the collonade footings at Curles Plantation in
Va. "Gaming piece" came to mind, but I decided instead that this
sherd had gotten into the river, become water-worn, was then hauled
up with sand which was laid as a footing for the brick walkway. What
troubled me was the incredible eveness of wear, regularity of the
size. Etc. Gizzard stone works for me. However it got there it helped
nail a TPQ for construction of the colonnade. Thanks again.
Dan
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