The alloy of copper with tin (bronze) was the first metallic compound in common use by mankind, and its use was extensive going back to prehistoric times. According to Pliny, the Roman supply was chiefly drawn from Cyprus, from which it gained the name cyprium, and from which is derived English word copper, the French cuivre, and the German Kupfer. Copper is a brilliant metal of a peculiar red colour which assumes a pinkish or yellowish tinge on a freshly fractured surface of the pure metal, and is purplish when the metal contains cuprous oxide. It is malleable and can be rolled into a thin sheet. It is also ductile and can be drawn out into a thin wire. Copper has two main oxidation states. Cuprite (Cu2O) is copper(I) oxide and tenorite CuO is copper(II) oxide. Copper with a charge of +1 is called cuprous; with +2 charge it is called cupric.
The colours of copper (II) complexes are explained by the behaviour of light passing through an aqueous solution. The visible spectrum for a solution of Cu (II), [Cu(H2O)6]2+, has an absorption band which spans the red-orange-yellow portion of the spectrum. Green, blue and violet are transmitted. So in relationship to the artist's colour wheel - colours on one side of the wheel are absorbed and their complementary colours are transmitted within a copper solution.
Copper sulphate in solution is blue. Add copper sulphate crystals to water. After several hours the copper sulphate will have dissolved, but will be more concentrated at the bottom. After several days diffusion will result in the concentration within the flask being the same everywhere. Adding a piece of zinc metal to the solution will create a displacement reaction. The solution loses its colour as copper is displaced by zinc and the zinc metal gets coated in red-brown copper metal.