On Facebook -JOIN I Antique Online.com: Collectors of Antiques and Collectibles.
Here is the link for the group https://www.facebook.com/groups/327133184409134/
Please join our FB group where YOU can post directly.
A Community For People Who Buy, Sell or Collect Antiques, Collectibles and Art
Ebony was the preferred wood that was used most frequently due to the rough play. If balsa you might get 1 game before they broke. Balsa is very weak, used for flyable model airplanes. I would guess they are celluloid which is an early form of plastic made from plant cells rather than petroleum. BTW, celluloid is VERY FRAGILE with age and will crumble with limited use. If any of your "bones" are broken look closely at the mixture. Black celluloid is dark black with lighter black swirls in it. Use magnification. Most sets have 27 tiles. Condition determines value.
My guess is that these dominoes are composite, most likely made of a molded and compressed sawdust mixture.
That would make sense, LB, thanks :)