Images
Formula: Na6K5Mn3+Mn2+14(Si9O22)4(OH)10.4H2O
Phyllosilicate (sheet silicate), manganese-bearing mineral
Crystal System: Monoclinic
Specific gravity: 2.78 measured, 2.579 calculated
Hardness: 3½
Streak: Light brown
Colour: Dark reddish brown
Environments
Plutonic igneous environments
Hydrothermal environments
Localities
At the type locality, Kukisvumchorr Mt, Khibiny Massif, Murmansk Oblast, Russia, armbrusterite was found in a
thin cancrinite - aegirine -
microcline vein within
urtite.
It occurs in intimate association with raite; other associated minerals are
lamprophyllite,
manganoneptunite,
pectolite, vinogradovite,
calcite, molybdenite,
galena, sphalerite and
fluorite. Armbrusterite occurs as split, curved crystals and
spherulites up to 2 mm in diameter. It is translucent, transparent in thin fragments, and dark reddish-brown with a
vitreous lustre
(AM 92.416-423).
Back to Minerals