I think I found the closest thing to vibranium that currently exists, Samarium, while I'm just barely getting into chemistry this is how I found it. Captain America's shield is made of Vibranium, Iron and carbon (which forms steel) as well as being painted with titanium oxide; in spiderman homecoming one of the answer to a knowledge bowl practice question is strontium, barium and vibranium ( which seems to be listed by their atomic numbers as Sr is 38, Ba is 56 and Sm 62, my theorized cousin element).

There are a number of exotic particles that have been recorded and could theoretically exist, these exotic particles replace other common particles ( protons and electrons) creating a exotic element, which could have different properties that the naturally occurring element.

All this means is vibranium could/may be a stable exotic form of samarium. This maybe produced in a similar way to Tony stark's new element.