Hisingerite

phyllosilicate

secondary mineral

Formula:Fe2Si2O5(OH)4.2H2O
Phyllosilicate (sheet silicate), generally amorphous, forms a series with neotocite.
Specific gravity: 2.43 to 2.67
Hardness: 2½ to 3
Streak: Yellowish brown, green
Colour: Black, brownish-black, dark brown, dark green
Environments

Plutonic igneous environments
Metamorphic environments
Hydrothermal environments

Hisingerite is a secondary mineral formed from weathering or alteration of iron-bearing silicates or sulphides by late-stage hydrothermal activity during sulphde ore deposition (Webmin, HOM). It is frequently found veining fayalite, enstatite or amphiboles, and sometimes siderite or wollastonite; it alters from pyrrhotite and possibly from chalcopyrite, and occurs as pseudomorphs after hedenbergite. It alters to nontronite (Dana). Associated minerals include olivine, pyroxene, pyrite, chalcopyrite and pyrrhotite (HOM).

At Llallagua, Bustillo Province, Potosi, Bolivia, hisingerite is common as amorphous masses, sometimes associated with cronstedtite (MinRec 37.2.140).

At the Wilcox Mine, Cowper Township, Parry Sound District, Ontario, Canada, hisingerite is intimately associated with pyrite and chalcopyrite. The ore occurs in garnet-biotite schist, and the hisingerite was formed mostly by the alteration of hypersthene (AM 46.1412-1423).

At the Montauban deposit, Mékinac RCM, Mauricie, Québec, Canada, the zinc and lead ores occur in limestone in a diopside and tremolite gangue. The hisingerite is largely a replacement of diopside. Complete pseudomorphs after diopside have been found here. Some of the hisingerite apparently formed as a replacement os calcic plagioclase and of siderite. The hisingerite is cut by veinlets of pyrite and of calcite (AM 46.1412-1423).

At the type locality, Riddarhyttan, Skinnskatteberg, Västmanland County, Sweden, hisingerite was found in the weathered zone of a cobalt and rare-earth-element polymetallic deposit, associated with pyrrhotite and pyrite (Mindat).

At the Manila mine, Cochise county, Arizona, USA, Hisingerite is observed as fibrous spherules associated with vanadinite, jarosite and wulfenite (R&M 90.4.343).

At the North Belmont mine, Santa Cruz county, Arizona, USA, fine pseudomorphs of hisingerite after pyrite have been found (R&M 94.2.162).

In the vicinity of Beaver Bay, Lake county, Minnesota, USA, hisingerite is a common alteration product in gabbro (AM 46.1412-1423).

At Babbitt, Mesabi Range, St. Louis county, Minnesota, USA, hisingerite is a common and locally abundant mineral in veinlets in the iron formation (AM 46.1412-1423).

Common impurities: Al,Mg,Ca

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