Describe the bug
Green Schist brick slabs from the Underground Biomes mod become Basalt brick slabs from the same mod when mined with any pickaxe (tested with stone, iron, bronze and diamond pickaxes).

To Reproduce
Steps to reproduce the behavior:
Place a single Green Schist brick slab (doesn't matter which half of the block it is placed) and mine it with any pickaxe.
Expected behavior
Green Schist brick slab is supposed to drop as a Green Schist brick slab when mined.

Screenshots

Info (please complete the following information):

• Modpack Version: 2.77.5
• Server or Singleplayer: Server
• Version the world was created on: 2.77.5

Additional context
When placing two Green Schist brick slabs to make a single block, they behave normally and drop as Green Schist when mined.

duplicate of #362