Vibration Isolation for equipment using granite?

One must be careful when using granite or other solid rock. They ring and they transmit energy through them very efficiently. So you would not want to use cones under a granite slab on a concrete floor. You would be transmitting the energy directly to the components. 

On the other hand, the mass is an advantage. So, to get the value without transmitting vibrations the slab needs to be isolated. So for instance elastomer pucks or Vibrapods under can isolate them from small vibrations. For my amp, I use an amp stand, with vibrapods on top of it, then the granite slab and springs on top of the granite. Mass works to my advantage here. 

But even better, as I use under most of my components are vibrapods on the rack shelf, then Black Diamond Racing platforms (very dense composite... really heavy), then springs on top of that, then component. This is a fairly slim profile.  

For my turntable I use a custom Silent Running Audio Ohio Class vibration platform. These guys make vibration platforms for electron microscopes and other really critical applications. It had a very significant effect on my Linn, Klimax turn table. I would say this is the highest level of vibration control, Townshend platforms are also transformative for speakers.

When I’ve tried 1" slabs under speakers it made the sound brighter and harsher, which I didn’t like (yes, this was a lazy ham-fisted attempt with just hockey puck footers). Didn’t find it worthwhile under components either, and they’re a PITA to handle at that size / weight.

However HRS has used thin slices of granite in combination with dissimilar materials (constrained layer damping) to apparent success - but that’s quite different to a singular slab of granite. 

You should consider using it in conjunction with something like sheets of Herbie’s grunge buster or generic sorbothane to control the ringing. Full coverage (thin sheet) is much more effective than just footers.

I try to avoid speculative theory, but I believe the primary resonance frequency of the support is more important than the speed of propagation in the material. And this particularly true in turntables where the suspensions are tuned to different frequencies.

This gels with my experience - the interaction between support structure (rack) and turntable suspension / plinth is going to matter a lot more than anything else, for some systems. Those on concrete slab can get away with much more here. I’ve had turntable & rack combos resonate in the audible bass range (really bad), in the subsonic "woofer flapping" range (REALLY bad - most rumble filters don’t attenuate this enough), and in the relatively safe sub-2Hz range (SOTA). 

I used as mulveling said a sandwich of different materials with success...

For stability reasons i stop using springs , my actual speakers being small desktop Edifier...

But i go on again  with absorbing special properties(low cost) bamboo plate, sorbothane, granite plate and concrete block... This coupling /decoupling work well especially with the fine tuned right amount of concrete block over my speakers for damping them..

All great replies. Thanks to all. I guess everything may have it's time and place, but no solution for all applications. To my ears my system does not suffer from any ringing or excess vibration issues to warrant tinkering, but each situation is different. I was just curious if his approach is justified. Now I can understand a heavy slab on top of a component, but with ventilation considerations that is probably not practical.