Instead of Stone, I would encourage you to use either MDF, HDF, or Corrian. These materials are more dense in an irregular manner. Stone, Grannite esp. is an amalgum of different metamorphic rocks with very regular crystaline structure, Marble is pretty soft and purous. If you still want to use Stone, use Granite, but do NOT polish it, allow the rough irregular surface to be present so as to remove the pollished mirror effect.
Happy listening
Happy listening