It would be nice to have red/black granite dust centrifuge recipes, for those who don't want to build with the stuff...
According to Wikipedia, granite is composed primarily of Feldspar, Quartz, and Mica, making it primarily silicon and oxygen but still with a good bit of aluminum, with lesser amounts of potassium, sodium calcium, iron, and even trace amounts of titanium and manganese. (There's a very nice little graph of average composition if you scroll down in the first link) Obviously balance should trump realism in this, but that should give you some inspiration for what a centrifuge recipe could yield.