Waste in the ponds produced by leaching gold from ore is a source of potential environmental dangers.
Gold can only be produced by leaching it from ore.
( z1 possible :ARG1 ( z2 produce :ARG1 ( z3 gold ) :manner ( z4 leach :ARG1 z3 :ARG2 ( z5 ore ) ) :mod ( z6 only ) ) )