Introduction with a question

[Henk]

Detlef,

I thought to recognize some of the whalebone structure on your pictures. Whalebone is not much more heavier than cow or buffalo bone. As tunggulametung wrote, the structure of whalebone is more spongier. Maybe you can make a clear picture from the inside of the wrongko. Maybe the unpolished part of the material could tell us more.
Whalebone seems to be not an unusual material for kerissheaths. I'm not familiar with your Mrs. Ghiringhelli and don't know why she doesn't know about this material.