Answer: The white tuff stone used for the Imperial columns was formed 90 million years ago by overlapping layers of sediment. Pressure exerted over eons re-crystallized this material, naturally petrifying it. It has extraordinary insulating capabilities and contains a large percentage of chalk which acts as a natural mold preventor. The capacity to regulate humidity is legendary as the tuff cellars in the Loire valley attest. The shelves are made of re-invorced stone.
