Red Sandstone

Red Sandstone is a solid block. It is a sedimentary rock found naturally at entrances of mesa caves, and can also be crafted from red sand. Unlike regular sandstone, it does not generate under the red sand floor, rather, orange stained clay does this job.

Chiseled Red Sandstone is a decorative form of red sandstone with a Wither carving on it.

Smooth Red Sandstone is a decorative form of red sandstone with a smoother texture.

Obtaining
Red sandstone can be mined using any pickaxe. If mined without a pickaxe, the block is lost.

Natural generation
Red sandstone generates naturally at most cave entrances in mesa biomes. The amount that generates is highly variable; some caves may generate a large amount of red sandstone, while others may generate just one block, or even none. Liquid pools will not generate red sandstone, resulting in floating red sand which will fall when updated.

Trivia

 * The idea of the Wither appearing on Chiseled Red Sandstone was suggested by Reddit user ULiopleurodon.
 * Jeb stated that "maybe one day" he might design a desert temple-like structure to generate in mesas, using Red Sandstone and its variants.
 * The red sandstone slab was the first to use a separate block ID from the rest of the stone slabs were to them being already occupied, similarly to the wood species added in 1.7. This is also why red sandstone (and wooden) slabs could not be used to craft armor stands in the initial 14w32a release, until the only usable slab became the stone slab.