Each tile is approximately 4mm deep and consists of a layer of metal foil sandwiched between two layers of glass; the layer of glass on top of the gold is a few mm thick while the one underneath is much thinner and is there simply to protect the back of the metal foil.  These tiles may be used on walls or floors but are not recommended for high-traffic areas.  They are UVA and frost-resistant and can be used outside in a carefully chosen location and should be interspersed with tiles in other materials to avoid creating a slip hazard.  They can be cut with wheeled cutters.