Magma crystals are a new item added with Nether X. They look like a red-orange nether
IMG 20140626 112545 kindlephoto-651740

The crafting recipes for magma crystals.

quartz. They can be obtained two ways. The first one is that they can be crafted by putting a nether quartz in a crafting table with a piece of magma cream. The second way is to blow up a magma block, which will yield zero to one crystal for every block blown up. Magma crystals cannot be made into tools. However, they can be made into armor that, when wearing the entire set, will give fire immunity.