It’s called Doctor Copper because you are meant to be able to tell the health of the global economy from the way it behaves.
And at the moment copper is looking pretty sick.
The price of the metal has fallen for two weeks in a row, and reached $6,376.25 a tonne, a low last touched in June 2010.
Analysts are blaming the decline, in part, on signs of weakness in the Chinese economy.
On Thursday of last week the latest batch of numbers out of Beijing showed industrial production grew at its slowest pace for more than four years during January and February.
Meanwhile, retail sales and investment were way lower than expected.
So demand has shrunk, and copper prices have been hit.