Block of Quartz

Blocks of Quartz are blocks made from Nether Quartz. Nether quartz blocks are going to be a "milky, limestone/marble" like, according to Jeb.

Trivia

 * Unlike most mineral blocks, this one is crafted with 4 of the base item instead of 9. Other 4:1 storage blocks include glowstone, snow and clay, but these cannot be reversed by crafting; they must be placed and mined to recover the original items (and in the case of glowstone, you usually don't get all of them).  (And then there are the brick and sandstone recipes, which are simply irreversible.)