A "tile file". Looks like a file, but with carbide grit.
Don;t go at it with anything powered. Marble is only soft, and you'll eat holes in it.
Wet or dry (black silicon carbide abrasive) will polish it. Woodturner's melamine polish is good for a final shine, but hard work to buff out.
pro's use oxalic acid to get the final hi gloss. Oxalic acid reacts with the calcium carbonate in the marble to produce calcium oxalate on the surface. It smoothes the marble finer than any abrasive could.
Don't ask me where to get it though
David
Order it from a proper chemist. You may have to sign some forms or other but if you've got a good reason, anyone can get it.
Only problem we had, was it came in a rather large vat rather than a small tub.
Toby.
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