Marble or Granite shelfs in a hifi rack?


Im planning to make a simple HIFIrack with marble or Granite shelfs and halfsize bricks in betwheen Is this a good idea?
It will be very heavy (20 or 30mm thicknes?) But will this isolate from vibration or perhaps pick up vibration? I have a wood floor.
If good is marble or granite to prefer?
128x128ulf
Well Brulee, I may not have yet made the plunge to begin seriously investigating alternatives, but I can agree with you about MDF. I suppose there may be worse materials one could employ, but on the whole I think the entire MDF paradigm is basically a scam rack makers (and retailers like Audio Advisor) have attempted to perpetrate on audiophiles in order to get away with using an easy and cheap shelf material.
Ulf, Neaunce is some type of composite shelf that absorbs vibration from floor and the component. If you dfo a search there was a long thread a month or two ago.
Sistrum is a rack system that uses Audiopoint cones to support the components. It channels vibes away from the components and out through the rack (no dampening, just removal). There is a review of it on Stereo Times web site, and the home page for Sistrum is on Star Sound Systems.