  The unusual properties of elemental plutonium have long been a puzzle. It has
been suggested that these properties may be related to quantum criticality [G.
Chapline, J. L. Smith LA Sci 26 (2000) 1]. In this talk we will describe some
experimental observations on rare earth and actinide materials which suggest
that there are pairing correlations in all f-electron metals, and that the
anomalous properties of the elemental actinides in the vicinity of
Np/Pu/Am,even at elevated temperatures, is associated with a critical point in
the variation of the density of paired electrons with atomic number.
