Millerite on calcite, Estabrook Park, near Milwaukee, WI. Pete Rodewald specimen and photograph.
LOCATION: Outcrops along the Milwaukee River in Estabrook Park (sec. 5 T.7N. R.22E.). Locality referred to variously as Berthlet, N. Milwaukee, Cementville, Lincoln Park, Capitol Drive, Washington Street Bridge and Humboldt St. Bridge.
ACCESSIBILITY: Levels currently inaccessible within park. Limited collecting is possible at low water levels.
GEOLOGY: Vugs in Devonian carbonates of the Milwaukee Formation.
Asphaltum - in cavernous zone in dolostone
Calcite - colorless rhombohedral xls. up to 1 cm. across.
Dolomite - rock-forming mineral in dolostone
Marcasite - iridescent bladed xls., also globular and concretionary masses.
Millerite - Fibers, sometimes radiating with individual fibers as much as 7 cm. long.
Pyrite - small xls. showing cube and octahedral faces.
Quartz - chalcedony lined geodes up to 8 cm. across.
Sphalerite - dark brown to black xls. up to 2 cm. across.
Zaratite - coating on millerite.
BIBLIOGRAPHIC REFERENCES: Bagrowski (1940); Eckert (1980).
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