In Michigan's Upper Peninsula there was most certainly more metals on the surface than today. In the past, the Old Copper Complex (6000 BP to 3000 BP) would make use of surface copper deposits to make their tools and decorative items. In Upper Michigan a lot of copper is in native form and mostly pure which means it is not an ore and does not need to be smelted. It can be easily formed and shaped into items. It wasn't until Europeans and European descendants arrived in the area that deep shaft mines were implemented to extract even more copper than what could be found on the surface. Almost every major mine in the Keweenaw Peninsula was built on a Native American pit mine. There are also several Native American pit mines that were discovered on Isle Royale in Lake Superior which were used seasonally to extract copper.