How DID The Ancient Egyptians Sculpt Granite?

I just saw some ancient Egyptian sculpture in a museum-the sculptures were of people, and very finely executued-in granite (a very HARD stone). I understand that the egyptains only had bronze chisels and tools-so how were they able to make sharp lines in hard rocks like granite?
Also, they were able to smooth their sculpture-what abrasive did they use?

Just throwing out some WAG until an actually knowledgeable person shows up.
1: Granite chisels.
2: Sand. Lots and lots of sand. But then, the Egyptians had access to a plentiful supply.

See page 4 for an explanation. Besides bronze and, later, iron tools, they used wooden hammers to bash it into general shape, then polished it with rubbing stones and sand pastes.