Cleaning chinese slate tiles?

[spotit3]

I have recently moved into a house and the floor in the kitchen is chinese slate tiles. There wasa black mat in front of the sink with some sort of rubber type backing and carpet on the front. You see these mats for sale everywhere. Unfortunately the mat was rather dirty and when I lifted it to dispose of it I discovered it had left the tiles beneath a very dark colour. I presume it has come from the backing of the mat and I can't seem to get those tiles back to the colour of the rest of the floor. Having said that, all the tiles could do with a good clean but I don't seem to be able to lift the dirt with any of the usual floor cleaners. Anyone have any idea how I could clean these slate tiles. All answers appreciated.

[woodchopper]

There are proprietary cleaners available for your type of tile - I have them in my kitchen and to be honest have never used the cleaners once as I hate the look of the tiles and because they are dont have an even surface and I may addd am going to rip them up in the next few weeks.
Use the proper cleaner for them and then use a sealer to keep them looking good.

[spotit3]

Thanks. I will look in the shops on Monday. By the way how do you propose to rip them up. I had thought of that but had imagined it would be too difficult to get rid of them!

[woodchopper]

Lump hammer and chisel - they are only grouted in.