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Formula: NaCaMn2+3Si5O14(OH)
Inosilicate (chain silicate), manganese-bearing mineral
Crystal System: Triclinic
Specific gravity: 3.46 measured, 3.465 calculated
Hardness: 6
Streak: White
Colour: Light pink to white
Common impurities: Fe,Mg
Environments
Localities
At the Tanohata mine, Tanohata, Shimohei District, Iwate Prefecture, Japan, marsturite is associated with
natronambulite and
mangano-ferri-eckermannite
(HOM).
At the type locality, the Franklin Mine, Franklin, Franklin Mining District, Sussex county, New Jersey, USA, marsturite occurs
as crystals up to 0.5 mm in size, implanted for the most part on abundant yellow
axinite-(Mn) and and epitaxially overgrown on
rhodonite, with willemite. The sequence of
formation is axinite-(Mn) containing euhedral colourless
willemite, followed by rhodonite,
followed by marsturite, hence marsturite is found coating willemite,
rhodonite and axinite-(Mn) and is the last
mineral to form
(AM 63.1187-1189). The marsturite occurs as a secondary mineral in
cavities in fractures traversing massive
franklinite-willemite-zincite
ore in a metamorphosed
zinc-manganese-iron
orebody hosted in the Franklin marble. Associated minerals include
ganophyllite and franklinite, as well as
rhodonite, axinite-(Mn) and
willemite
(Mindat, HOM).
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