Linked from
The 10 pages that link to Tantalum, each with the reason it gives.
PegmatiteRelated: Rare-element pegmatites can concentrate tantalum in minerals such as tantalite.
ColtanRelated: Its value drives most commercial extraction of coltan.
TantaliteRelated: Tantalum is the defining high-value element concentrated in tantalite.
Tantalum carbideRelated: Tantalum supplies the metal framework in tantalum carbide.