Adamantium is a man made metal that is totally indestructible.
History
Adamantium is a man made metal that is totally indestructible and can slice through nearly any substance on Earth. It was created by the Weapon X program that was part of the Canadian government.
Wolverine gained his adamantium claws after he went through the Weapon X process.
Yuriko Oyama later gained adamantium claws after the Reavers put her through the bonding process which also turned her into a cyborg. After this she took the name Lady Deathstrike.
When Spider-Man first fought Scorpion, Scorpion hit Spider-Man's hand with his metal tail. This injured Spider-Man's hand and Spider-Man jokingly asked if Scorpion's tail was made out of adamantium.
Hammerhead early in his life had adamantium bonded to his skull which made his head a flattop. The adamantium made Hammerhead's skull so strong that he could ram through solid objects by hitting them with his head while running at his top speed.
Iron Man made one of his armored suits out of adamantium. The adamantium suit was stolen by the Mandarin and he attempted to use it to kill Iron Man. However, Iron Man had complete control over the adamantium armor even while he wasn't inside of it. Iron Man was able to control the adamantium armor and defeated Mandarin.
Later on Mandarin had his men steal liquefied adamantium from Stark Enterprises. However, the adamantium they stole turned out to be a fake planted by Iron Man.