  We present a neutron and x-ray scattering investigation of Ca$_3$LiOsO$_6$, a
material predicted to host magnetic ordering solely through an extended
superexchange pathway involving two anions, an interaction mechanism that has
undergone relatively little investigation. This contrasts with the ubiquitous
superexchange interaction mechanism involving a single anion that has well
defined and long standing rules. Despite the apparent 1D nature and triangular
units of magnetic osmium ions the onset of magnetic correlations has been
observed at a high temperature of 117 K in bulk measurements. We experimentally
determine the magnetically ordered structure and show it to be long range and
three dimensional. Our results support the model of extended superexchange
interaction.
