How Good Is A Marble Slab at Deadening Vibration

I have a marbles slab that is approx. 42" X 16X 2". A left over insert from a coffee table. I would like to lay it on top of a plant stand table that is 50" X 18X 30" The slab weigh about 70 lbs. II think I have enough space laterally to position a Rega turntable, a Bel Canto line stage, and Rega Apollo CD player and a pair of Red Dragon monoblocks, that could easily be stack vertically if necessary.(Also could place them on the bottom shelf which has a slight V-shaped dip ...probably a run off channel. This would save me three feet of speaker cable on both channels is placed near the bottom)

The plant stand is made of wood and has fairly massive "L-shaped" legs. The table weight is about 40 pounds.

My thinking is that a marble slab should provide excellent isolation from vibration. The only drawback is the left side of table will only be a foot from the right speaker. So I would start the progression of components from right to left to increase the distance to the speaker in question. Would like opinions from members about the pros/cons of this set-up. Thanks, Jim