  Neutron scattering measurements have been performed on deuterated powder
samples of claringbullite and Zn-doped claringbullite
(Zn$_x$Cu$_{4-x}$(OD)$_{6}$FCl). At low temperatures, claringbullite
Cu$_4$(OD)$_{6}$FCl forms a distorted pyrochlore lattice with long-range
magnetic order and spin-wave-like magnetic excitations. Partial Zn doping leads
to the nominal ZnCu$_3$(OD)$_{6}$FCl compound, a geometrically frustrated
spin-1/2 kagome antiferromagnet that shows no transition to magnetic order down
to 1.5 K. The magnetic excitations form a gapless continuum, a signature of
fractional excitations in a quantum spin liquid.
