  We investigate the turbulence statistics in a {multiphase plume made of heavy
particles (particle Reynolds number at terminal velocity is 450)}. Using
refractive-index-matched stereoscopic particle image velocimetry, we measure
the locations of particles {whose buoyancy drives the formation of a multiphase
plume,} {together with the local velocity of the induced flow in the ambient
salt-water}. {Measurements in the plume centerplane exhibit self-similarity in
mean flow characteristics consistent with classic integral plume theories.} The
turbulence characteristics resemble those measured in a bubble plume,
{including strong anisotropy in the normal Reynolds stresses. However, we
observe structural differences between the two multiphase plumes. First, the
skewness of the probability density function (PDF) of the axial velocity
fluctuations is not that which would be predicted by simply reversing the
direction of a bubble plume. Second, in contrast to a bubble plume, the
particle plume has a non-negligible fluid-shear production term in the
turbulent kinetic energy (TKE) budget. Third, the radial decay of all measured
terms in the TKE budget is slower than those in a bubble plume.} Despite these
dissimilarities, a bigger picture emerges that applies to both flows. The TKE
production by particles (or bubbles) roughly balances the viscous dissipation,
except near the plume centerline. The one-dimensional power-spectra of the
velocity fluctuations show a -3 power-law that puts both the particle and
bubble plume in a category different from single-phase shear-flow turbulence.
