I did a Google search and found this: http://www.zrci.com/zrci001.pdf
Supposedly it can be machined with carbide tooling. I would expect tool life might be short and I am not sure I would want the dust getting into my machines. Here is a description stolen from a different website:
"Any of several forms of aluminum oxide, Al2O3, occurring naturally as corundum, in a hydrated form in bauxite, and with various impurities as ruby, sapphire, and emery, used in aluminum production and in abrasives, refractories, ceramics, and electrical insulation. Also called aluminum oxide."
The idea of filling my machine with an abrasive dust doesn't turn me on.