My fireplace has 1" cubes of tungsten, aluminum, and magnesium, plus a cube of selenite and quartzy-style synthetic prism, all arranged on little stands really close to the floor, so reachable by children. Neighbor 2.5 year old last year was very put out when he couldn't lift the W cube. It is really a lot of fun to hold. Dropping it on one's foot is ill-advised, particularly if you are 2.5 years old.