Abstract The Caledonia Mine, owned by Red Metal Explorations, is located near Mass, Michigan (Fig. 1). The Caledonia Mine is southwest of the Mass and Adventure Mines (Fig. 2) within an area of native copper deposits outside of the major deposits of the Keweenaw Peninsula native copper district, some 40 km southwest of a major producer, the Baltic Mine (see Fig. 3 of Bornhorst, this volume). The mines of the Mass area worked the Evergreen, Ogima, Butler, Mass, South Knowlton and Knowlton mineralized flow top lodes, termed the Evergreen Series, over a total strike length of about 5 km. The Evergreen Series produced about 33 million kg of copper at grades between 0.5 and 1.25 % (Weege and Pollack, 1971) . The Mass Mine, largest producer in the area, produced 23 million kg of refined Cu while the Adventure Mine produced 5 million kg from 1851 to 1923 (Butler and Burbank, 1929). The Butler, Evergreen, and Knowlton lodes were the most productive of the flow tops; the Butler was the largest. The other flow tops yielded only small amounts of copper.

Abstract This road log runs from the Portage Lake area of the Keweenaw Peninsula, north and east to Copper Harbor located in the eastern end of the peninsula (Fig. 1). The road log is designed to provide coverage of all major lithologic units within the Keweenaw Peninsula segment of the middle Proterozoic Midcontinent rift system (Fig 2). Many of the stops include examples of the effects of late compressional faulting and of native copper mineralization and associated burial metamorphic alteration. Stops include roadcuts, lakeshore outcrops, old mine waste rock piles and a private mine. The Michigan Tech Earth Science Laboratory and Experimental Mine and the Caledonia Mine are described separately. The present problems of access to stops described here are minimal, but please respect private property and use low profile outdoor principles. Also note that old mine dumps can be hazardous where bad ground occurs. The user should refer to introductory articles for stratigraphic nomenclature, geologic background, and discussion of native copper deposits. Several stop descriptions used here are revised from previous guidebooks first authored by Bornhorst (Bornhorst, 1989; Bornhorst et al., 1986; Bornhorst et al., 1983). Extra stops have been added beyond the formal SEG field trip for the benefit of users of this guidebook.