  Deuteronium jarosite, (D_3O)Fe_3(SO_4)_2(OD)_6, contains a kagome lattice of
Heisenberg spins, S=5/2, with a coverage of 97+-1%. DC and AC susceptibility
measurements show strong in-plane antiferromagnetic exchange
(\theta_CW=-1500+-300K) and a spin-glass transition at T_f=13.8 K, while the
magnetic contribution to the specific heat below T_f rises with T as T^2,
characteristic of two-dimensional propagating modes. Powder neutron diffraction
reveals short-range magnetic correlations (\xsi=19+-2 \AA) with a wavevector
corresponding to the \sqrt{3}x\sqrt{3} spin structure at 1.9 K.
