  A dark matter halo model is developed postulating a new state of matter,
entities which have internal spin-like terms. Their motion in an external
Schwarzschild metric is discussed. The internal spin motion contributes to the
centrifugal force along with the usual orbital angular momentum term and can
severely limit the distance of closest approach to the attractor. An
energy-momentum tensor associated with an aggregate of them is shown to have
primarily pressure-like components. A model of the spiral galaxy halos is
developed which can match the observed `flat' rotation curves of some galaxies.
The halo dark matter `missing mass' results from the pressure term's
contribution to the metric tensor. A possible rationale for the presence of the
cosmological constant is discussed. An addendum to the standard cosmology
picture allows an estimate of the amount of dark matter; this is in reasonable
agreement with that observed. It is possible that the adopted representation of
the internal spin motion could be replaced by a boson string Lagrangian.
