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Formula: Ba(Na,Ca,Y,Ce,K)(CO3)2.2.6H2O
Anhydrous normal carbonate, mclelveyite group,
barium-, yttrium- and
cerium- bearing mineral
Crystal System: Hexagonal
Specific gravity: 3.25 to 5 measured, 3.37 calculated
Streak: White
Colour: Bluish green, pale greenish gray
Common impurities: TR,La,Pr,Nd,Gd,Tb,Dy
Mildly RADIOACTIVE
Environments
Carbonatites
Hydrothermal environments
Evaporite deposits
Localities
At the Kirovskii apatite mine, Kukisvumchorr Mt, Khibiny Massif, Murmansk Oblast, Russia, ewaldite is associated
with kukharenkoite-(Ce),
belovite,
fluorite, nenadkevichite,
ancylite-(Ce), synchysite-(Ce),
mckelveyite-(Y),
burbankite,
calcite, baryte and
orthoclase
(HOM).
At the Kola Peninsula, Murmansk Oblast, Russia, ewaldite is found in
carbonatites and hydrothermal veins in alkaline igneous
rocks
(HOM).
At the Dolyhir Quarry, Old Radnor, Powys, Wales, UK, ewaldite crystals were typically striated, translucent,
pale yellow-brown
hexagonal pyramids to 3 mm, associated with harmotome,
witherite, alstonite and
calcite, and typically intergrown with
mckelveyite-(Y) and
donnayite-(Y).
Ewaldite is late in the primary paragenesis; clearly it
postdates
harmotome and also appears to be later than
calcite. The barium which must have
been present in
solution for ewaldite to form may have been provided by dissolution of
witherite or
alstonite. Ewaldite is typically formed in lacustrine (lake)
evaporite deposits, but here
it occurs in hydrothermal alpine type veins
(M&M 25.23, MW).
At the type locality, the Diamond Alkali Daco No. 3, Sweetwater County, Wyoming, USA, ewaldite has been found
in drill cores
into trona beds in dolomitic
marlstone. Associated minerals include
mckelveyite-(Y), shortite,
labuntsovite,
leucosphenite,
searlesite and hematite
(HOM).
Indications are that ewaldite and mckelveyite-(Y) are
paramorphs,
except for possibly different water contents
(AM 56.2156).
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