has long been valued as a precious metal More abundant than gold, silver metal has in many premodern
monetary systems functioned as coinable specie sometimes even
alongside . . .
Iron is a relatively abundant element in the universe. It is
found in the sun and many types of stars in considerable
quantity. Iron nuclei are very stable. Iron is a vital
constituent of plant and animal life, and is the . . .
rare earth element (REE) or rare earth metal
(REM), as defined by
is one of a set of seventeen
chemical elements in the
periodic table, specifically the fifteen lanthanides, as well as scandium and yttrium. . .
Coltan (short for columbite/tantalite and known
industrially as tantalite) is a dull black metallic ore from which the
elements niobium and tantalum are extracted. The niobium-dominant
mineral in coltan is columbite . . .