@GAW9576
Not sure, but that blank may be an "Invisavue" blank .... I bought some from Woodcraft, but they are no longer available, it seems.
They used to be available in single colors with a chunky "crystalline" appearance (black, white, red, green, blue), and then there was a black and white blank called "Moo Cow" with the appearance like you show but with the black and white in more nearly equal amounts.
I'd love to get some more of the white if anybody has some to sell or trade.
I found this material to be difficult to drill and turn because it would heat up and melt. . Had to take it very slowly and with light cuts.
There was definitely a slight ridge on both sides of the round blank, just like the pics of your cutoffs seem to show.
It was more expensive than other materials. . It was beautiful when polished up. . Made pens for my wife and my sister in white.
The chunks in the white appear to have subtle rainbow coloring in the right lighting. . I don't have any of the white, but I may have other colors including the "Moo Cow".
Send me a PM if you wish, and I will look.