  A phase diagram of argon based upon percolation transition loci determined
from literature experimental density-pressure isotherms, and simulation values
using a Lennard-Jones model shows three fluid phases. The liquid phase spans
all temperatures, from a metastable amorphous ground state at 0K, to ultra-high
T. There is a supercritical mesophase bounded by two 2nd-order percolation
transition loci, and a gas phase. Intersection of two percolation loci in the
p-T plane thermodynamically defines an equilibrium line of critical density
states.
