  An overview is given of experimental data on Heisenberg Spin Glass materials
so as to make detailed comparisons with numerical results on model Heisenberg
spin glasses, with particular reference to the chiral driven ordering
transition scenario due to Kawamura and collaborators. On weak anisotropy
systems, experiments show critical exponents which are very similar to those
estimated numerically for the model Heisenberg chiral ordering transition but
which are quite different from those at Ising spin glass transitions. Again on
weak anisotropy Heisenberg spin glasses, experimental torque data show well
defined in-field transverse ordering transitions up to strong applied fields,
in contrast to Ising spin glasses where fields destroy ordering. When samples
with stronger anisotropies are studied, critical and in-field behavior tend
progressively towards the Ising limit. It can be concluded that the essential
physics of laboratory Heisenberg spin glasses mirrors that of model Heisenberg
spin glasses, where chiral ordering has been demonstrated numerically.
