Ewaldite

ewaldite

mckelveyite-(Y)

labuntsovite

leucosphenite

Images

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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