[NHCOLL-L:3714] ID of Shell versus Ivory/tusk

[Bob Glotzhober]

Our archaeologists have an Archaic age (circa 4,000 ybp) gorget that
they are curious about. The older records indicated it was shell, but
they thought it might be ivory. I looked at it, and it seems to fit. The
gorget came from Glacial Kame culture - and with the rich supply of
mastodon and mammoth fossils found in Ohio, it could just as easily been
made from tusk ivory as from shell (we have some large species of
mussels in Ohio currently, and they did have trade with Gulf Coast
cultures and had marine shell also available.

 

So the question is, how to separate shell from ivory.

My first thought was a test for calcium carbonate with weak HCl acid -
the destructive sampling approach was not warmly received, but we do
occasionally approve destructive sampling in the right circumstances. 

 

My next thought was doing the old Archimedes trick to determine density
of the object and compare that to known shells and known ivory. Does
anyone have a source of existing, standardized density for shell and
ivory?

 

Are there any microscopic analyses that can be done without making thin
slices? Any other tests that anyone might suggest?

 

We await your ideas, suggestions and tried and true methods.

 

Bob Glotzhober

 

============================================ 
Robert C. Glotzhober                bglotzhober at ohiohistory.org 
Senior Curator, Natural History             Ph. 614/ 297-2633 
Ohio Historical Society 
1982 Velma Avenue 
Columbus, Ohio  43211-2497 

 

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