Sand

Sand is a fairly common block found near Water on normally generated  maps. Like Gravel, it is affected by gravity and will fall to the lowest solid block in the y-axis it is located or placed in. It is possible to suffocate if sand falls on top of the  player.

In Indev, Infdev and Alpha, sand can be smelted into Glass. In Indev on a floating islands map, there is also an occasional chance to find floating platforms of  sand and/or Gravel connecting islands together. However, removing a floating sand/gravel block or adding a block to the landmass may cause  all the blocks to fall down their z-axis. The effect can be reproduced by placing sand on top of a Minecart, as the bottom layer  will not fall once the minecart is removed.

If a sand block falls onto a Torch or Step, it will disintegrate into a sand resource; this can be used to create self-sealing hallways. (See Airlock.)

History
Sand was removed in revision 0.0.19a due to lack of room in the UI, but returned in version 0.0.20a.

A glitch was present in single player for quite some time that caused water to flood from blocks affected by gravity if placed against a wall but not on the ground. The bug has since been fixed.

Trivia

 * By very slightly covering the edge your player with sand using the manipulation of gravity, you can see tunnels, caves, and even large lava  flows on Alpha.