I am turning Marblewood today. Have looked into it before turning. It is a hard wood and looks very nice when finished. Kind of a chocolate reval type look. Be sure to match the two blanks since it has different color grains. Very hard on sinus'. Just like Cocobolo on the sinus'. Vacuum when sanding and wear bandana or resprator if possible. Tough on tools. Finish with Carnuba Wax and then a coat of CA, and the blanks will look like glass. Any color pen kit looks great!
Steve