our hearth had some very ugly ceramic tiles laid over 6 in sq red tiles. i've removed the ceramic tiles and cleaned up the original red tiles, but now i see that they are all scratched as if they were scored to enhance the glue for the ceramic tiles. how can these scratched be removed? i don't know what kind of tile this is, but it must be heat resistant as it was laid into the firebox. the house is 102 years old. thanks!