Now if I may trump your nerdiness:
While the vibration absorbing aspect of Wakandan Vibranium does make it tough it's material hardness is weaker. Vibranium, for example, can be bent by your typcial strongman; only Thor and the Hulk have even dented Adamantium.
While it's hardness is not greater, Antarctic Vibranium has the property of reducing the hardness of other metals until they become liquid and has on at least one occasion caused Adamantium to melt (Avengers v2 #20 IIRC).
And Adamantium is theoretically weaker than the material in Captain America's shield which is ofter erroneously called Adamantium but is in fact an alloy of Wakandan Vibranium and another unknown material. The shield was introduced in Captain America #2 way back in 1941 while Adamantium was invented after the foundation of the Avengers. The official stance is that the shield is stronger than Adamantium.