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Formula: La(CO3)(OH)
Carbonate, bastnasite group,
lanthanum-bearing mineral,
paramorph of kozoite-(La)
Crystal System: Hexagonal
Specific gravity: 4.75 measured, 4.778 calculated
Hardness: 4
Streak: White
Colour: Light brown, light honey-yellow, colourless
Common impurities: Nd, Ce
Environments
Plutonic igneous environments
Carbonatites
Localities
In the Nikšic Municipality, Montenegro, both
hydroxylbastnäsite-(Nd) and
hydroxylbastnäsite-(La) occur
(JWW pps 268-270)
There are two co-type localities, Mochalin Log, Kyshtym, Chelyabinsk Oblast, Russia and the Vuoriyarvi
alkaline-ultrabasic massif, Northern Karelia, Murmansk Oblast, Russia. Final approval is based on material from the
Vuoriyarvi complex
(Mindat).
At Mochalin Log, Kyshtym, Chelyabinsk Oblast, Russia, hydroxylbastnäsite-(La) occurs as light brown grains up
to 0.2 mm included in massive
aggregates of other light rare earth element minerals:
allanite-(Ce),
ancylite-(Ce),
bastnäsite-(Ce),
bastnäsite-(La),
biraite-(Ce),
biraite-(La),
ferriperbøeite-(Ce),
fluorite,
percleveite-(Ce),
percleveite-(La) and
törnebohmite-(La)
(MM 88.6.755–765)
At the Vuoriyarvi alkaline-ultrabasic massif, Northern Karelia, Murmansk Oblast, Russia,
hydroxylbastnäsite-(La) occurs as clusters (up to 1 mm) of light brown, honey-yellow or colourless hexagonal
tabular to short-prismatic crystals up to 0.15 mm, associated with fluorite
and ancylite-(Ce) in cavities of
calcite–dolomite
carbonatites
(MM 88.6.755–765)
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