Question

A label for a plant is made of copper. When it is first put in a garden,it is bright and shiny. After a few months, the label has a dull, greenish color. When you rub your finger over the surface, some soft material rubs off. What happened to the copper?

Answer 1

Easy. It oxidized. Its called verdigris. That is the name of the pigment that turns the copper green.

Answer 2

It reacted with the water and water vapor and oxygen in the air, causing it to rust, and form copper oxide.
Hope this helps!