Slab

Slabs are half-versions of their respective blocks.

Obtaining
Stone-type slabs require a pickaxe to mine. Wooden slabs can be mined with anything, but an axe is quickest.

Natural generation
Stone slabs can be found naturally in villages lining the roof of blacksmith shops and inside some of the buildings where they form counters. They are also found in strongholds where they are used in some of the stairs, ledges and torch pillars. Sandstone slabs can be found naturally in desert villages, desert wells, and desert temples. Double stone slabs can be found in villages, in the butcher's shop and in blacksmiths.

Crafting
Wooden slabs must be crafted entirely from one type of wood, but by the same token, they keep the type and color of the wood used, thus "Birch Wood Slabs" and so forth.

Placement
Slabs can be placed either right side up or upside-down:
 * Pointing at a block top or the bottom half of a block side will place the slab right side up.
 * Pointing at a block bottom or the top half of a block side will place the slab upside-down.

Behavior


Slabs are treated as a whole block by other blocks and liquids. Two slabs of the same type can be placed one on top of one another to make a full-size block, but different slab types cannot be mixed in this way.

Redstone can be connected to the wire on the side of the slabs. Redstone placed on top of an upside-down slab can receive signals from an adjacent block of redstone one block lower but cannot transmit signals to it. This is why "ladders" made from upside-down slabs, as pictured to the right, can transmit redstone signals up, but not down.

Mobs see a slab as a full block. Therefore, by placing an upside down slab above a slab with a block in between, there will be sufficient space for the player to walk through. Mobs, however, will see one block of space in between and won't get through (Fixed by 1.8.1). This does not apply to baby zombies and spiders, because they are only one block tall, and to slimes, as they will hop towards the player even if there is something obstructing the way. Mobs can also spawn on top of upside down slabs and on double slabs, but not on lower slabs.

Due to the way blast rays propagate from an explosion, bottom-half slabs provide extremely effective absorption to explosions directly on top of them.

Despite how sneaking lowers the player's eye level half a block, doing so does not allow the player to walk over a single slab with one block of air above it because of the player's true height. A player cannot walk from a block of soul sand to a slab without jumping. The player can walk off a slab while sneaking.

If you set a slab on the top half side of any block under water, it will displace as much of it as a whole block. Not only can you grab a quick breath of air, but you can see as clear through the water as looking over the land above the surface than in it itself.

Minecarts on powered rails will not be repelled from a slab. They will, however, be repelled by a slab with a minecart on top.

Data values
The slab blocks use IDs and data values to differentiate between types. They also have block states which will replace data values in the future.

Double stone slabs

 * Block 43


 * Block 181

The full stone, sandstone, quartz and red sandstone slabs have a top texture on all sides.

Stone slabs

 * Block 44


 * Block 182

Double wooden slabs

 * Block 125

Wooden slabs

 * Block 126

Double stone slabs
minecraft:double_stone_slab

minecraft:double_stone_slab2

minecraft:purpur_double_slab

Stone slabs
minecraft:stone_slab

minecraft:stone_slab2

minecraft:purpur_slab

Double wooden slabs
minecraft:double_wooden_slab

Wooden slabs
minecraft:wooden_slab

Trivia

 * Slabs let a small amount of light pass through their edges. This light is only visible with Smooth Lighting is turned on, and does not affect mob spawning or other light-dependent processes.
 * The exception of this is that any light directed through a slab does not affect any block's light values north of the source.