What is the color of copper corrosion?

When copper corrodes, it develops a distinctive green layer on its surface. This green coating is often seen on old copper roofs, statues, and pipes exposed to air and moisture for a long time.

Why Does Copper Turn Green?

Fresh copper starts out with a shiny, reddish-brown color.

Over time, when copper is exposed to air and moisture, it reacts with oxygen, water, and carbon dioxide.

These reactions form a mixture of copper carbonate and copper hydroxide. This mixture creates the famous green layer called a "patina" or sometimes "verdigris".

How the Color Changes?

1. Copper doesn’t turn green overnight. Here’s how the color transformation usually happens:
2. First, the copper darkens to brown as it forms copper oxide.
3. Later, with continued exposure, the surface changes to a blue-green or gray-green color as the patina develops.

Everyday Examples 

• The Statue of Liberty in the USA is a classic example—its green color comes from the corrosion of its copper skin.
• Many old buildings with copper roofs or domes also show this greenish hue.

Copper corrosion is green in color. This green layer forms naturally over time and actually helps protect the copper underneath from further damage. So, if you see copper that looks green, it’s just nature’s way of giving the metal a protective (and beautiful) coat