I've installed many a tile and hardwood floor as a day job, maybe I can offer a few considerations to think about. You've stated that you want to be as eco as possible, and durable & long lasting, and natural stone tiles are pretty eco and very durable, but can be quite expensive. Then you have porcelain tiles, which are more durable and hold up better than ceramic tiles, so skip ceramics. Porcelain usually costs less than natural stone. So porcelain is man made and may contain "chemicals" in the tile as well as the glaze, but has been vitrified and is inert once fired, and won't leech any residue or emit vapors. Natural stone won't gas off vapors. A ton of
energy was used in the kilning process to fire the porcelain twice, once for the tile, second for the glaze. The machines that harvested the natural stone burned
petroleum, so did the vehicles to transport it from the quarry to the final destination. Those natural stone tiles were likely polished by a machine, consuming energy. I think it's splitting hairs now, but neither option would fall under any category of being toxic (that branch of eco), like say, synthetic carpet for example. Some natural stones even when polished can stain (like a drop of ketchup left too long on a granite countertop for example), whereas glazed porcelains do not, as far as I know. I think you
should choose what fits the budget and meets your tastes. I hope this is helpful
