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Formula: NaNa2(Mg4Mn3+)Si8O22(OH)2
Inosilicate (chain silicate),
eckermannite root name group,
sodium amphibole subgroup,
amphibole supergroup,
manganese-bearing mineral
Crystal System: Monoclinic
Specific gravity: 3.16 measured, 3.186 calculated
Hardness: 6
Streak: Pinkish white
Colour: Cherry-red to very dark red
Luminescence: No fluorescence under long wave or short wave UV
Environments
Sedimentary environments
Metamorphic environments
Mangani-eckermannite is a new mineral, approved in 2023 and to date (February 2024) reported only from
the type localty.
Localities
At the type locality, the Matsumaezawa pit, Tanohata mine, Tanohata, Shimohei District, Iwate Prefecture, Japan,
mangani-eckermannite occurs as prismatic crystals up to 0.3 × 0.2 mm and their aggregates up to 1 mm
intergrown with braunite,
vittinkiite and quartz.
Mangani-eckermannite is cherry-red to very dark red and reddish-brown in thicker grains. It is translucent
with a pinkish white streak and vitreous lustre
(MM 87, 935-942).
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