The iron paid the wages and the copper mineral paid the collectors. French Creek Mines, at St Peters in Chester County, is listed by the USGS as a past producer with iron as the primary commodity and copper second, working magnetite ore. It shows up in the record under two other names as well, the Kleim Mine and the Elizabeth Mine, which is worth knowing if you go looking through old references.
Its reputation is not about tonnage. Writing in the Mineralogical Record in 1994, R. A. Sloto and L. L. Dickinson described French Creek as a popular and prolific mineral collecting locality for over a century, and singled out what it is famous for: chalcopyrite in spectacular specimens, alongside fine cubic and octahedral pyrite crystals and octahedral magnetite.
That combination is the appeal. Chalcopyrite is a common enough mineral that most specimens are unremarkable, so a locality that produces it in genuinely fine crystals earns a name among collectors that has nothing to do with how much ore came out. The same goes for the magnetite: octahedra with clean faces are a different proposition from the massive ore that made the mine economic.
The USGS logs the deposit as small, and that is the honest frame for the place. This was never a great American iron district. It was a modest working whose walls happened to hold crystals worth crossing a state for, and it has been drawing collectors since the nineteenth century on that basis alone.
Chester County was among the first parts of Pennsylvania to be settled, so the ground here has been examined, dug and written about for a very long time. Treat any visit as one to private or managed land, and find out who holds it before you arrive.
Magnetite & fine specimens
Other places on the map within a couple of hours.
