Netherrack

"Netherrack was added to the Java edition of Minecraft in Alpha version 1.2.0, the Halloween Update, alongside pumpkins, clocks, fishing and the Nether. Spoiler alert: the Nether is where netherrack gets its name from (though it was originally called "bloodstone", eww), and it's also where you'll find more netherrack than any one person could ever need."

- Duncan Geere

Netherrack is a rock-like block found in the Nether.

Natural generation
Netherrack makes up most of the Nether's terrain.

Post-generation
Netherrack generates as part of nether portals spawned floating.

Crimson or warped nylium transforms into netherrack if a solid, opaque block is directly above it.

From block loot
Netherrack can be mined only with a pickaxe.

From mob loot
Endermen can pick up netherrack, and drop the block if killed while holding it.

Info
When netherrack's top is lit on fire, the fire burns indefinitely.

bone meal on netherrack placed next to warped nylium or crimson nylium transforms the netherrack into more nylium.

Breaking
Netherrack can be mined only with a pickaxe.

Sounds
Java Edition:

ID