Chopped ice or something like that. Maybe Ed (Exotic Blanks)will have an answer.
It is some of that old time material like celoplast or old casein material.
I remember that material. It was hard to drill, melted if you had the wrong wattage bulb over the drill press. It sure did finish up pretty. Yours sure did, that's a beautiful pen! I think I've still got a piece in black and white somewhere.
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