A lot of the ores in minecraft are based on real rocks and minerals. Not all of the minecraft ores have real life counterparts.
Geologists generally like rocks and like it when other people like rocks too. The British Geological Survey (the organisation which is responsible for making and updating all the geological maps of the British Isles) have made a geological minecraft map. You should check it out. Mindat (the professional online database for minerals and mineralogists) has also produced a guide to the rocks of minecraft and tries to match up some of the real life counterparts.