H2O's EU5 Mod Workshop 中文

Keweenaw

The Keweenaw Peninsula projects northeast into Lake Superior, enclosing Keweenaw Bay along its southern shore. Its rocks hold rich deposits of native copper, worked by Indigenous people thousands of years before industrial mining began. Fires heated the rock around a copper mass, and cold water cracked it; stone hammers and chisels then freed the metal. Copper was fashioned into tools and later into ornaments.

References

  1. en.wikipedia.org/wiki/Keweenaw_Peninsula