Psilomelane is “abundant” in drill core from NW SW sec.
Psilomelane is associated with pyrolusite and a number of primary and secondary copper and iron minerals at the copper prospect 4 miles NW of Gratiot (SE NW sec. Although not very commonly found in jewelry there are many uses for this unique mineral and stone. Agnew (1963) notes it as common in the Platteville district, especially in the SE portion. The Germany Psilomelane Dendrite stone can be found under a variety of different names, such as the Black hematite or Psilomelane chalcedony. LAFAYETTE COUNTY: Psilomelane and other manganese minerals are wide-spread as “black ocher” along joints in the oxidized zones of the many Upper Mississippi Valley zinc-lead deposits in the county (Heyl, et al., 1959). Beautiful specimens are found in museums, including the Seiman museum at Michigan Tech (Dickey, 1938 LaBerge, 1984). Psilomelane forms as a weathering product of other manganese minerals, as concretions or dendrites deposited by ground water or as nodules precipitated from lake water. R.2E.) as spectacular large botryoidal banded masses lining cavities in the iron formation. IRON COUNTY: Romanechite was common at the Montreal Mine (NE NE sec. It is particularly notable as a component of earthy “wad” in the old lead pits in sec. IOWA COUNTY: Psilomelane and other manganese minerals are wide-spread as “black ocher” along joints in the oxidized zones of the many Upper Mississippi Valley zinc-lead deposits in the county. The ore ran 22-31% manganese and occurred in layers up to 15 cm. Psilomelane is associated and intergrown with iron oxides such as hematite and goethite and other manganese oxides such as pyrolusite.ĭUNN COUNTY: Psilomelane is found as bog manganese ore in the SE sec. Psilomelane as “manganese dendrites” are ubiquitous along joint surface in much of the bedrock of the state. Such nodules have been found at various places in Green Bay, for example (Rossman et. Psilomelane forms as a weathering product of other manganese minerals, as concretions or dendrites deposited by ground water or as nodules precipitated from lake water. The term is so loosely used, and the substance referred to usually so superficially examined that all reported psilomelane and romanechite localities are grouped together below. Most, but not all, psilomelane is the mineral romanechite (BaMn 2+Mn 4+ 8O 16(OH) 4 ).
Psilomelane is used as a blanket term to denote a variety of hard massive mixtures of manganese oxides. (Photo by Andrew Silver.)įormula: Mixture of hydrate manganese-barium oxides Geological Survey Denver Library Photographic Collection. From the mineral collection of Brigham Young University Department of Geology, Provo, Utah, Mineral Specimens 832. Psilomelane Psilomelane with pen for scale.
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