Generally stocks and metals have a negative correlation between them, however, we don't trade many pairs of stocks and metals. The reason? Their correlations are too weak to be a good candidate for a pairs trade.
However, when looking at various metals against themselves, we see a much stronger, but not perfect correlation. This makes metals a good pairs trading opportunity against different metals.
Silver has been an under-performer this year, so a potential trade may be silver relative to another metal.