Is it normal for quartzite to have "natural cracks"?
In the picture attached you can see the grains, it is very rough on the touch
Yes. A good and proper buffing and seal should make it smooth, at least IME.
While on topic anyone know of a good service that does this? Mine are about 2 years old and a very light color... need to reseal..... Looking for a Jersey based place. While I think it looks great and would install them again, definitely not as forgiving as Quartz.