on their own in an unknown manner. The ultra-resilient alloy was used to create Captain America's shield. MacLain worked for decades (without success) to duplicate the accident. However, during an experiment in the 1960s, he developed the virtually indestructible metal adamantium. When T'Challa became king of Wakanda, he strove to end his country's isolation from the rest of the world. Making the existence of vibranium known to the outside world around the mid-1980s, he sold small quantities of it to foreigners who, he believed, would not use it to harmful ends. T'Challa used the profits to enrich and modernize his nation. Over the years, many have tried to obtain or affect the mound of vibranium at Wakanda, but for the most part Wakanda has kept it safe, and become quite powerful in the process. During their Secret Invasion of Earth, the Skrulls assumed the identity of S.H.I.E.L.D. agents and enslaved natives of the Savage Land to mine Anti-Metal. They also invaded Wakanda. The Wakandans successfully repelled the attack. When Wakanda was politically overtaken by the xenophobic Desturi, they granted Doctor Doom access to the country's vibranium vaults. Fearing Doom would use it to amplify his mystical energies, T'Challa activated a failsafe he had developed that rendered all processed vibranium inert. The rumors about its alien origin had later been proven true, as while most of earth's vibranium had been all but liquidated, certain planetary systems carry an ample supply of the element deep within certain extraterrestrial biospheres, as was the case with a refugee planet that the Spartax Empire tried reclaiming during Captain Marvel's space travels. In the wake of the continuity-wide spanning reboot of the Marvel multiverse chronicled in Secret Wars: Battleworld, vibranium's abundance in Wakanda and beyond has re-flourished to sizable quantities, and the mutant criminal Vanisher was absconding and selling Wakandan vibranium on the black market in New York City. When a small sub-molecular imperfection was introduced into Captain America's shield, each impact over the years spread to neighboring molecules. It grew until the molecular bonds of the shield were completely broken down, shattering the shield. The shattering effect continued to spread to other vibranium, unconnected to the shield. This created a vibranium "cancer", a shock wave propagating throughout the world. It violently detonated any vibranium it found, from mineral deposits to components of ships or equipment. The shock wave was traveling to the "Great Vibranium Mound"