What Are These Scales Made Of?

[mjclark]

I really like the scales on this pre-1911 US-made Durham Duplex and US-made Bowdin's Wedge from about the same time.
But what is it?
It's creamy yellow with transverse stripes:

 

[mjclark]

Ivorine a faux Ivory.

Thanks - that sounds like a Led Zeppelin track