CU, AU, AND ZN-PB SKARN DEPOSITS (MODELS 18b,c; Cox and ...

that resulted from reported environmental damage (SCS Engineers, 1984). These include deposits where historic
mine tailings contribute to water quality degradation and, in some cases, affected aquatic life. The extent of
degradation from historic mining appears to be related to the magnitude and duration of operations as well as deposit
type and climate. Any area that was extensively mined for long periods of time is likely to have experienced some
environmental impact.
Skarn deposits that enter production today cannot be compared with skarn deposits worked a hundred, or
even twenty, years ago. Many currently active mining or exploration projects involving skarn deposits operated at
some time in the past at a smaller scale and are currently being re-evaluated for different metals (gold, silver) than
were sought in past enterprises. Many abandoned or inactive skarn deposits are the focus of recent exploration
because of economic changes or development of modern technology that allows previously uneconomic ore to be
mined. For example, skarns that were mined in the past for base metals or tungsten may now constitute exploration
targets for gold. Known or potential environmental hazards from historic mining can, in some cases, be mitigated
by reopening the site to mining activity that involves reprocessing historic tailings using modern mining practices.
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