“Copper prices have a lot to do with silver prices because you have a significant amount of silver produced as a byproduct of copper. So if you look at the relationship between metal prices and and silver mine production, you’ll find that mine production is more responsive to copper prices and than it is to silver prices, because only about 25%-30% of silver comes from silver mines but a larger percentage comes from copper mines. So when the the copper price is high and producers are increasing their copper production you tend to see an increase in byproduct of silver production that is larger and more dynamic than the increase you see in silver mine production from primary silver mines when the silver price rises.
-quote from an interview with Jeff Christian on the David Lin YouTube channel.
