Hi All,  I have received the following very interesting information
and link which sheds much light on this debate:

  "Piano ivory was _never_ elephant tusk ivory.  Of what did come
from elephants was so miniscule it doesn't count.  The tusks that
made hundreds of millions of pianos came from northern Alaska and the
Siberian Straits.  I used to have a newspaper picture showing a work
crew gathered for a group picture.  It was a mining camp and in the
background were two literal _mountains_ of black mastodon tusk to be
shipped to the States.  There is no such thing as the 'common wisdom,'
since it's always wrong.  Thought you'd like to know."

http://www.nps.gov/archive/bela/html/heritage.htm 

Thanks to Craig Brougher.

Regards,
Paul Brennan