The earliest natural stone flooring was recored in the 13th century BC. Glazed and colored bricks were used to make low reliefs in Ancient Mesopotamia, most famously the Ishtar Gate of Babylon (ca. 575 BC), now partly reconstructed in Berlin, with sections elsewhere. Mesopotamian craftsmen were imported for the palaces of the Persian Empire such as Persepolis. Now lets fast forward, oh a couple of thousands of years and look at the advancement of the tile we use on todays flooring. There are eight types of that are used in todays flooring: sandstone, cantera, slate, flagstone, granite, travertine, marble, and limestone. Most of the tile that I see today is slate and travertine and out of these two travertine is 90% of the time. Travertine has a beautiful natural look with small pockets of holes and when polished could have a shine. Natural stone is recommended to have protectant/sealant because its absorbent and can stain easily.
So when should you clean your natural stone tile? Well, I recommend once a year. Natural stone is vary absorbent, stains easy, scratches easily, and can loose its beauty quickly. So cleaning it once a year would help maintain its natural beauty.