I think this is Cambrian Black (Not Cambria ES) and is easier to deal with than AB Black.
it's got a patina on it. When this stuff is honed and enhanced, it's fairly easy to take care of, but when it's cleaned with soaps and stuff over the years it becomes a nuisance.
Do what Stu said, but I would definitely enhance, use MB-21 Ultimate enhancer. We have been using that enhancer specifically for honed black granite since 2008 and have found that it is the best. When used correctly, it reduces smudging, but you have to wipe ALL the excess off and convince the customer to let it cure for 24 hours before really putting it back to use.
Maintain it with MB-23 or Easy Stone Care Ultimate spray polish on a regular basis. Honed black granites need a regular polishing with a light duty spray polish.
Jeff Kondra started with this polished piece at our last class
and ended up with this