Gneiss is often the first major league ore that up and coming miners graduate to. Finding the more expensive variation of Gneiss, called Iridescent Gneiss, is a major coup for these miners.
Gneiss is a popular ore type because it holds significant volumes of three heavily used minerals, increasing its utility value. It has a quite a bit of mexallon as well as some pyerite and isogen.
This ore is a compressed and much more dense version of the original ore.