Fossilized Mammoth Ivory and a Discourse on the Antiquities Trade

Looking for some guitar parts, I came across many references to fossilized mammoth ivory. The native Siberians find the tusks sticking out of the permafrost and sell them to dealers, who sell them to craftsmen (scrimshaw, pool cues, guitar parts, etc).

http://www.canadafossils.com/mammoth_ivory.html

My friend thinks this is unethical - I don't, however. But I subscribe to a couple archaeology magazines and there is also a raging debate over antiquities dealers. Many objects - Greek amphorae, Roman oil lamps - are as plentiful as Coke bottle. But other things should belong to nations, not individuals.

Do you or your family own any such antiquities, and how do you justify it?