> Metals are able to deform plastically. A metallic bond is not so directional, and you typically thing of all the molecules in a metal as a big blob with a clo

> Metals are able to deform plastically. A metallic bond is not so directional, and you typically thing of all the molecules in a metal as a big blob with a cloud of electrons that can freely move about (also the reason for good electrical conductivity). Also the reason why metals absorb electromagnetic radiation on a very broad spectrum. Which means it's very difficult, if not impossible, to make materials that behave mechanically like metals (hard, yet not fragile) but are transparent.