Rainbow Brick

Type	BrickCrafting material
Placeable	✔️ (1 wide × 1 high)
Use time	15 (Very fast)
Rarity	(Desktop, Console and Mobile versions) ; (Old-gen console and 3DS versions)
Research	100 required

Waterfalls changing color by using Gemspark Blocks and Rainbow Brick. Gemspark Blocks' effects are disabled when they are offline.

Rainbow Brick is a Hardmode brick that can be obtained as a drop from the Rainbow Slime. It glows in the dark and cycles through the colors of the rainbow. The cycling colors of Rainbow Bricks, Rainbow Brick Walls, Helium Moss, Helium Moss Brick, Helium Moss Brick Walls, Rainbow Torches, the Disco Ball, and Rainbow Hair Dye are synchronized with each other.

If a waterfall passes through a Rainbow Brick, it will also cycle through the colors. Rainbow Bricks will not change the color of lavafalls, honeyfalls, or shimmerfalls(Desktop, Console and Mobile versions).

Crafting

Recipes

Result	Ingredients	Crafting station
Rainbow Brick	Rainbow Brick Wall4	Work Bench

Used in

Result	Ingredients	Crafting station
Rainbow Flare(Desktop, Console and Mobile versions)10	Flare10 Rainbow Brick	By Hand
Rainbow Torch(Desktop, Console and Mobile versions)10	Torch10 Rainbow Brick	By Hand
Rainbow Brick Wall4	Rainbow Brick	Work Bench

Trivia

(Desktop, Console and Mobile versions)Rainbow Bricks as they appear on the map, as of 1.4.4.

(Old-gen console and 3DS versions)Rainbow Bricks as they appear on the map before 1.4.4.

In Celebrationmk10(Desktop, Console and Mobile versions) and getfixedboi(Desktop, Console and Mobile versions) worlds, Underground Cabins are occasionally made of Rainbow Bricks.
Rainbow Bricks are one of the hardest types of blocks to obtain, because they generally never occur in the environment, cannot be crafted, and only drop from Rainbow Slimes. Despite this, Rainbow Bricks still only have a rarity of (Desktop, Console and Mobile versions) 01* / (Old-gen console and 3DS versions) 00*.
When placed, Rainbow Bricks will either have the rectangular texture of a standard brick, such as a Gray Brick, or a uniform blank appearance, such as that of a Smooth Marble Block. It may also change between one and the other when hammered. This can make it a rather tedious building material to use.
Rainbow Bricks will still maintain their rainbow-glowing effect even when painted.
Rainbow Bricks appear as a gradient when viewed on the map.