Although research has highlighted the importance of zinc for the immune system, because the mineral has many complex roles in the body it is not understood in any detail how it helps fight off infection.

BBC: Zinc 'keeps immune system in check'

Its interlocking cogs of power and influence -- geopolitical, regional, governmental, tribal, mineral, criminal, spiritual, clan and family -- are fiendishly complex.

CNN: Mali's conflict turns musicians into military

These are after all mines, often big mines, and the minerals extracted require complex and challenging refining to separate the chemically similar constellations of rare earth elements that are always collocated in various mineral concentrations and combinations.

FORBES: Tech's Mineral Infrastructure - Time to Emulate China's Rare Earth Policies