Assessment of undiscovered porphyry copper deposits within the range of the northern spotted owl, northwestern California, western Oregon, and western Washington

Geochemical analyses of rock samples from the Black Butte district and Holderman Mountain area, Lane County, Oregon

“…The clustering of these deposits into discrete districts and the characteristics of many of the districts have led some researchers to propose that the major vein districts may be underlain by porphyry copper-type deposits (Power, 1984). Indeed, there is indication that a porphyry copper deposit underlies the North Santiam district (Diggles, 1991). High-grade breccia-pipe copper deposits like that recently discovered at the Bornite property in the North Santiam District (Hladky, 1993) are associated with several porphyry copper districts in the Cascade Range in both Oregon and Washington.…”