Ceramic tiles contain a number of advantages over other floor coverings; they come in a variety of colours and designs, they clean up easily with regular sweeping and mopping and they don't rot or become saturated with moisture. However, for all ceramic tile's upsides, it also has its pitfalls. Bare metal scraped over ceramic tile can leave behind ugly deposits that mar the look of the tile. While tiles with deeper scratches may need to be replaced, you can easily remove surface metal in most cases.
Wipe the tile with a damp, soft cloth to remove dirt and loose flakes of metal.
Moisten a soft cloth with white vinegar. Wet the cloth, but not to the point of dripping.
Scrub the metal deposit with the vinegar-soaked cloth. Continue until the metal scratches disappear or it becomes obvious that the vinegar won't remove all of the metal.
Spread non-gel toothpaste over the metal deposit if the vinegar didn't work. Rub the toothpaste gently with a soft cloth to polish the metal streak off the tile. Continue until the metal disappears.
Wipe the toothpaste off the tile. Wash the area with a clean, damp rag to remove the remnants of the vinegar, toothpaste and metal.
You can also try using brass polish or a "Magic Eraser"-type cleaning sponge to remove the metal. Replace the tile with the metal streak if no cleaning options remove the deposit.