Quartz, or nether quartz, is randomly appearing item spawned upon activating the Nether Machine.
Quartz can be crafted into blocks with different designs. Quartz can mainly be used for pillars, because they look so much like marble. Quartz can also be crafted into Stairs.
In the pc version you had to visit the nether, dig deep in lava filled underground nether caves, go under a lava stream, find the quartz ore, go back into the real world, place the block again, mine it and get the quartz stick, craft them to get the quartz ingot, smelt it and recieve one quartz item, thingy.