Gravel

"Gravel has been a part of Minecraft since May 2009, when it was added to the game alongside other basics like sand, coal, and trees. Unlike those blocks, however, it's always been largely decorative - spawning in pockets underground that really get in the way when you're digging a tunnel, or in small quantities on beaches and near pools of water."

- Duncan Geere

Gravel is a block that is affected by gravity.

Obtaining
Gravel can be broken using any tool, but a shovel is the quickest. When broken, it has a 10% chance of dropping flint instead of the gravel itself. The flint received can be controlled with enchantments. Silk Touch removes the chance of dropping flint. Fortune increases the chance to 14% at level I, 25% at level II, and 100% at level III.

If gravel falls onto a non-full block, it will drop as an item, and not drop flint.

Natural generation
Gravel is found underground in veins of up to 33 blocks, generated at a rate of approximately 3.29% that of stone between layers 1 and 111.

In the Nether, gravel generates naturally in large veins between Y=63 and Y=65 in one-block-deep layers. It often generates without blocks below it, in which case it falls when updated.

Gravel is also found on beaches, near small pools of water, and underwater covering the ocean bottom.

Gravel is renewable in Console Edition only, due to the fact that you can reset the nether in the world options.

Usage
Gravel, if there is no block below it, will fall until it lands on the next available block. When gravel is being affected by gravity and falling, it exhibits a smooth falling animation.

If gravel lands on a mob or the player and covers their head, it will suffocate them until they destroy the block, move out of the block or die. If falling gravel lands in the space occupied by a non-solid block, (such as torches, slabs, rails, or redstone dust) or soul sand, it will break and turn into a gravel item. If it falls onto a cobweb it will slowly fall until it has gone through it completely, or until it touches the ground, at which point it will drop and turn into a gravel item.

Gravel can be placed on a non-solid block without falling.

Trading
Fletcher villagers have a 50% chance to buy 10 gravel and one emerald for 10 flint as part of their first tier trade.

Trivia

 * Explosions will launch falling gravel.
 * If gravel falls into a cobweb, it will be slowed down and then converted to an item.
 * If a player is standing on a stack of sand or gravel, and the stack falls on a non-solid block, the player will fall fast enough to take damage or even die.
 * Gravel will often fall into caves making a mock dead end. Thus, if a player encounters a gravel dead-end while mining, removing the gravel may reveal additional passageways.