From the PA Geological Survey

From the PAGS, this report is a compilation of information about companies that extract and sell commodities such as construction aggregate, agricultural lime, and similar materials, some of which have highly specialized uses.

This informational page is provided by Susquehanna County

This provides some useful data on non-fuel mineral production including salt, fire clay, iron, lead, zinc and others.

Though not updated since 2004, still a useful reference on PA iron furnaces.

1927 thesis by Franklin E. Ulf, Jr. about a history dealing with the early charcoal iron furnaces in Centre County.

This hobbiest's page has a nice listing of furnaces with photos, etc.

Information on a silver mine in Sweden Township in Potter County.

Geology guide to the Pequea Township Park

Geocache near the Pequea mine

by Donald Wise, from Pennsylvania Geology v.36, no.1 (2006):2-13.