I've turned this material several times and I agree it is like alternative ivory. Not near acrylester, but it is "chippier" than good PR blanks.
One piece of advice, the ends of ALL resin pens are important. Whether you sand to the brass or use a sharp mill, the ends are where all plastics are MOST LIKELY to chip. Round them over EARLY in your turning and be more careful as you approach the end. When the blank is finished, if the ends are not smooth, or there are smaill imperfections, (chips, if you will) the pen is likely to crack, starting at the point of the "chip".
This is true of ALL plastics I have turned but, recently, I have seen more evidence and formulated this "deduction".
I welcome discussion--here or by PM or in a new thread so we don't hijack this one.
EXCELLENT looking pen!!!! More frugal and more stable than real casein!!! Also polishes easier!