Uranium is more concentrated in the ocean than other transition metals because it forms a stable anion (UO4(2-), IIRC). The most abundant transition metal in th

Uranium is more concentrated in the ocean than other transition metals because it forms a stable anion (UO4(2-), IIRC). The most abundant transition metal in the ocean is actually molybdenum, followed by vanadium; most TMs have negligible solubility. But lithium with its high solubility is much more abundant in the ocean than any transition metal. Bromine is even more abundant than lithium in the ocean, but we don't extract it from the ocean; most of the world's bromine comes from the Dead Sea, and despite the location the supplies of Br is considered secure and the price is low. Processing large quantities of seawater is annoying, even though the energy cost in principle is attainable.