Green wood does damp but still rings. Dry it out ad it gets worse.
You want something that doesn't ring and that has mass to block vibration coming up from below.
I use 2" thick slabs of Brazilian granite - I used to use a large cement paving stone but was redoing the kitchen and had to buy a slab, and there was extra, so - a nice polished slab for both systems. Works very well mass loading and damping, just don't set it on a resonant base.
You want something that doesn't ring and that has mass to block vibration coming up from below.
I use 2" thick slabs of Brazilian granite - I used to use a large cement paving stone but was redoing the kitchen and had to buy a slab, and there was extra, so - a nice polished slab for both systems. Works very well mass loading and damping, just don't set it on a resonant base.