Hi lbphathead19:
I am not sure about quartz flagstone being slippery but I understand that flagstone does flake off from the salt exposure in a salt water pool. We definitely did not want anything that flaked off or was slippery. We informed our PB that we wanted a pool that was low maintenance and he recomended Quartzite which is what you see in the pic. So far we are happy with it.

Salt has little to do with the wearing of many flagstones. They tend to be sedimentary rock, are often softer than other materials, somewhat porous and layered, and subject to temperature change induced wear.

Scott