How to polish granite and basalt boulders?

There are diamond grinding attachments available for angle grinders and I like the idea of using the cement mixer to knock off some of the corners. I would tend to think the rocks will hold up longer than the mixer though. One thing that you should keep in mind is that the grinding dust is deadly. Talked with a stone carver in Vermont and he and his fellow carvers do not do granite because it will severely shorten lifespan. People who do this literally suffocate to death over time. Whatever you try, get yourself an expensive face mask and do whatever you need to keep your work wet. Some of the projects I read about make me envious that I am not involved but this is not one of them.