Carnes Quarry (Johnson Materials Co.)
Copper mine near the site of the present day Carnes Quarry, Douglas County, Wisconsin, circa 1900. Photo courtesy of the Wisconsin State Historical Society.
LOCATION: East of South Range, SW SW SW sec. 31 T48N R.12W, Douglas County, Wisconsin
ACCESSIBILITY: Posted private property, periodically active quarry
GEOLOGY:Tilted and faulted amygdaloidal Keweenawan basaltic lava flows. Flow top structures visible. Minerals mostly fill amygdules, or are found in veins and along faults.
Augite - in groundmass, also as phenocrysts. Largely replaced by epidote and chlorite.
Calcite - white cleavable massive.
Chlorite - massive, fine-grained scaly and spheres on quartz xls.
Chalcopyrite - massive, brassy to slightly iridescent.
Epidote - abundant as crystals in amygdules, also massive replacement of primary minerals in the basalt groundmass.
K Feldspar - pink massive adularia in amygdules. Also euhedral xls. showing pseudo-rhombohedral habit, with quartz
Plagioclase -as phenocrysts and in basalt groundmass. Largely replaced by epidote and other minerals.
Prehnite - green botryoidal, crude xls in amygdules.
Quartz - several habits: clear to white massive, locally euhedral xls. several cm. long, also sky blue massive, smoky massive and as pale white, tan or pink banded agate.
Unknown - Insoluble greenish fibers with epidote, etched from massive calcite. Actinolite? Pumpellyite?
COMMENTS: colorful combination of quartz, (massive and agate), K feldspar, epidote, chlorite and calcite in amygdules in black basalt.
BIBLIOGRAPHIC REFERENCES: Cordua, 1995 field notes.
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