Pyrosmalite-(Mn)

minerals

friedelite

bementite

willemite

Formula: Mn2+8Si6O15(OH,Cl)10
Phyllosilicate (sheet silicate), pyrosmalite group, forms a series with pyrosmalite-(Fe)
Specific gravity: 3.13
Hardness: 4½
Streak: Brownish yellow
Colour: Light brown
Common impurities: As,Zn,Mg,Ca,H20
Environments

Metamorphic environments

Pyrosmalite-(Mn) occurs in metamorphosed iron and manganese ores (Webmin).

Localities

At Broken Hill, New South Wales, Australia, pyrosmalite-(Mn) occurs in association with iron-bearing johannsenite and calcium-poor bustamite (AM 41.581-591). Also with rhodonite, manganese-bearing fayalite, manganese-bearing hedenbergite and galena (HOM).

At the Takanosu mine, Japan, pyrosmalite-(Mn) occurs with spessartine, manganese-bearing tremolite and quartz (HOM).

At the type locality, the Sterling mine, Sterling Hill, Ogdensburg, Franklin Mining District, Sussex county, New Jersey, USA, pyrosmalite-(Mn) occurs in veinlets in the franklinite ore of a metamorphosed stratiform zinc deposit, associated with friedelite, bementite and willemite (HOM, Dana, AM 38.755-760).

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