 right|thumb|250px|keweenaw peninsula. the keweenaw peninsula ( , sometimes locally /ËkiËvÉnÉË/) is the northernmost part of michigan's upper peninsula. it projects into lake superior and was the site of the first copper boom in the united states. as of the 2000 census, its population was roughly 43,200. its major industries are now logging and tourism, as well as jobs related to michigan technological university and finlandia university. ==natural==  the ancient lava flows of the keweenaw peninsula were produced during the mesoproterozoic era as a part of the midcontinent rift. this volcanic activity produced the only strata on earth where large-scale economically recoverable 97 percent pure native copper is found. much of the native copper found in the keweenaw comes in either the form of cavity fillings on lava flow surfaces which has a lacy consistency, or as "float" copper, which is found as a solid mass. copper ore may occur within conglomerate or breccia as void or interclast fillings. the conglomerate layers occur as interbedded units within the volcanic pile. the keweenaw peninsula and isle royale, formed by the midcontinent rift system, are the only sites in the country with evidence of prehistoric aboriginal mining of copper. artifacts made from this copper by these ancient indians were traded as far south as present day alabama.public law 102-543 (oct. 27, 1992); 106 stat. 3569 these areas are also the unique location where chlorastrolite, the state gem of michigan, can be found. right|thumb|250px|copper island the northern end of the peninsula is sometimes referred to as copper island (or "kuparisaari" by the finnish immigrants), although this term is becoming less common. {{cite web |url= h
Copper Extinct_volcanism Geography_of_Houghton_County,_Michigan Geography_of_Keweenaw_County,_Michigan Landforms_of_Houghton_County,_Michigan Landforms_of_Keweenaw_County,_Michigan Peninsulas_of_Michigan Regions_of_Michigan Rift_volcanism Upper_Peninsula_of_Michigan