Ed,
Certainly some Elephant Ivory from the white keys of a very old piano for me almost impossible to show the styrations and detail black of the African Ebony keys. Reminds me of my long long former life as a photographer when the brides wore white and the grooms black when we used to selectively tone to acheive facial colour sepia and use cow gum over the blacks to preserve them. In the 70,s we had a 120 yr old Photo Studio and all portraits were B&W hand coloured until colour neg film burst onto the market. So the only Ivory used was the whitish keys the pen and black keys are African Ebony and the other pen Faux Ivory. I tend to state as I did initially the material but this time sid not itemise sorry. Mostly running from one thing or another the syndrome retired people develop.
Kind regards Peter.