Glass

Glass is a block that first appeared in Creative version 0.0.18a_02. It has an almost completely transparent texture put on all six sides of the block. Glass is not a natural block, and is never generated as part of the terrain. Glass blocks adjacent to other glass blocks are invisible when viewed through glass. Sunlight can penetrate through glass, making glass useful for buildings such as greenhouses. Although glass breaks very quickly with no tool, swords can be used to hasten the process slightly with a penalty of one extra use per block destroyed.

Torches, Jack-O-Lanterns, Minecart Tracks, Doors and Ladders can not be placed on glass.

Glass blocks are crafted by smelting a block of Sand. When broken, the glass block will be completely destroyed and no blocks will be dropped.

Notch has expressed low-priority desire to implement tile-to-tile support so when Sand comes into contact with Lava, it creates Glass.

Trivia

 * In Survival Test mode, glass blocks could be broken very quickly and would drop a glass block to pick up. The only way to obtain glass blocks at that time was to place them on the map before the level was loaded in the client.
 * Notch has plans to make lava turn sand into glass naturally in a future version of the game.
 * When water is above glass, an infinite source cannot be created.
 * When attempting to light glass on fire with the Flint and Steel, the durability of the tool is lowered without any flames appearing.
 * Arrows will not break Glass when fired at it.
 * Placing a glass block on top of a chest does not prevent the chest from being opened.

Glas