In materials science, “plastic” refers to the ability of a material to undergo permanent deformation under stress without breaking. Metals exhibit plasticity when they are subjected to stress beyond their elastic limit, allowing them to be shaped or formed. This property is distinct from the common use of the word “plastic” to describe synthetic polymers.
Perhaps you meant to say that ices are crystals?
No. In astronomy, everything heavier than hydrogen or helium is referred to as metals. So, a star’s metallicity would be including carbon, oxygen etc.
In my country we refer to gravel roads as metalled roads, for no reason I can explain.