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Formula: NaNa2(Mg4Sc)(Si8O22)F2
Inosilicate (chain silicate), double chains,
eckermannite root name group,
sodium amphibole subgroup,
w(OH,F,Cl)-dominant amphibole group,
amphibole supergroup,
scandium-bearing mineral
Crystal system: Monoclinic
Specific gravity: 3.097 calculated
Hardness: 5 to 6
Streak: Bluish grey
Colour: Light yellow to light blue
Luminescence: Not fluorescent
Magnetism: Non-magnetic
Environments
Carbonatites
Metamorphic environments
Scandio-fluoro-eckermannite is a new mineral, approved in 2024 and to date (February 2026) reported only
from the type locality.
Localities
At the type locality, the Bayan Obo deposit, Bayan Obo, Bayan Obo mining district, Baotou City, Inner Mongolia,
China, scandio-fluoro-eckermannite was collected from
banded Fe-REE ores that have formed due to the
fenitisation caused by
carbonatite intrusion. Associated minerals include
monazite, bastnäsite,
magnetite, biotite,
fluorite, bazzite,
thortveitite and
magnesio-fluoro-arfvedsonite. The
scandio-fluoro-eckermannite occurs as euhedral to subhedral crystals and aggregates, appearing both as inner
zones of a crystallisation sequence from scandio-fluoro-eckermannite to
magnesio-fluoro-arfvedsonite, as well as homogeneous
fine-grained particles, reaching up to 350 μm in size and about 7 wt% in Sc2O3 content.
Scandio-fluoro-eckermannite displays a light yellow to light blue colour under plane-polarized transmitted
light; it is non-magnetic, and non-fluorescent. The hardness is 5 to 6 by analogy to
eckermannite, and the calculated specific gravity is 3.097
(AM 111.2.277-288).
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