natronambulite

rhodonite

serandite

arfvedsonite

Natronambulite

Images

Formula: NaMn2+4Si5O14(OH)
Inosilicate (chain silicate), forms a series with nambulite, rhodonite group, manganese-bearing mineral
Specific gravity: 3.51
Hardness: 5½ to 6
Streak: White
Colour: Pinkish orange
Common impurities: Fe,Mg,Ca,H2O
Environments:

Pegmatites
Metamorphic environments

Localities

At the type locality, the Tanohata mine, Tanohata-mura, Shimohei District, Iwate Prefecture, Japan, natronambulite occurs in contact metamorphosed low-grade banded manganese ore (Mindat, MJ 12.332-340), associated with manganoan aegirine, manganoan arfvedsonite, quartz and rhodonite. It also occurs as an accessory mineral in an albite-microcline-quartz pegmatite cutting the ore (MJ 12.332-340, HOM), associated with aegirine, manganoan arfvedsonite, rhodonite, mangano-ferri-eckermannite, marsturite, serandite, quartz, albite and microcline (HOM).

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