Drawn as an underground mine, reached by a shaft or tunnel and worked along the ore. The ore color stands for crushed, broken limestone nec. Federal records note the kind of operation and its status, not its depth or layout, so this is a typical example rather than a survey of this site.
This is an active mining operation regulated by MSHA (Mine Safety and Health Administration). Active mines operate under federal safety standards and are subject to regular inspections. If you live near an active mine, the operator is required to comply with environmental regulations including dust control, water discharge permits, and noise standards. Contact your state environmental agency if you have concerns about a specific operation.