Limestone has been enriched with silver and lead from mineral-rich fluids driven by underlying plutons in the Silver Island Mountains, Tooele County.
A pluton is a body of magma that cools and crystallizes deep within Earth’s crust, and is typically granitic in composition. Utah’s wealth of rich ore deposits is in large part due to the plutonic process. During pluton emplacement, minerals form in surrounding rock. Limestone and dolomite in particular are prime host rocks for mineralization and concentrations of ore.