No tile can be installed without grout. Grout is what locks the installation together into a monolithic whole. Even stone tile will have small differences in sizes that dirt will get into if it's not filled with grout.

Old fashioned stone installs involved much thicker stone set into a thick mudbed, with the stone site cut to fit very closely. Then the stone dust was combined with Portland to form the grout and smoothed over the whole install, which was the polished in place. That type of work doesn't exist anymore, except in a very few places around the globe with very old craftsmen.