So does anyone know what the first mosaic artwork installation was?
DO you mean the "new" mosaic artworks such as the murals at 36th St. Brooklyn, etc? If that's what you mean, I don't know for sure, but it had to be some time after 1989. Essex St's primitive mosaics (that are now being covered over) were the first attempt they made to make mosaics, and that was in the 1989 renovation. The Graham Ave recreation of a small piece of mosaic recreating the Canarsie line's ceiling band over a utility room at the extreme east end of the station was the first attempt I saw to actually "recreate" mosaics. They are also a bit primitive by today's standards, but much better than Essex. I don't have a photo of that, but that was in 1991. My guess would be that the mosaic artwork had to come some time after that point in 1991.