what kinds of natural materials can give coloring on copper like patina process?

Answer 1

Copper is like any other metal; in the presence of moisture and oxygen, it develops an oxide coating.

A lot of metals simply turn a darker shade of the same color as the original material, or else develop a dark brown or gray hue that is often called 'patina'. A couple of materials - like iron and copper - become a completely different color. Iron oxide is a definite reddish color (referred to as 'rust'), while color of the copper oxide formed is a green tint, and is often referred to as 'verdigris'.