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Formula: La2Si2O7
Sorosilicate (Si2O7 groups) of lanthanum
Crystal System: Tetragonal
Specific gravity: 5.094 calculated
Hardness: 6
Colour: Very pale yellow to colourless in thin fragments to light yellow in aggregates
Luminescence: Does not fluoresce under ultraviolet light.
Solubility: Does not react with either cold hydrochloric or nitric acids.
Environments
Percleveite-(La) is a relatively new mineral, approbed in 2019 and to date (November 2024) the only confirmed
occurrence is at the type locality.
Localities
At the type locality, Mochalin Log, Kyshtym, Chelyabinsk Oblast, Russia, percleveite-(La) was found in
polymineralic nodules, associated with allanite-(Ce),
allanite-(La),
bastnäsite-(Ce),
bastnäsite-(La),
ferriallanite-(Ce),
ferriallanite-(La),
ferriperbøeite-(Ce),
ferriperbøeite-(La),
fluorbritholite-(Ce),
hydroxylbastnäsite-(Ce),
perbøeite-(Ce),
perbøeite-(La),
törnebohmite-(Ce) and
törnebohmite-(La). Percleveite-(La) occurs as isolated
anhedral grains commonly up to 0.2 mm × 0.4 mm and very rarely up to 1 mm × 1 mm. It is transparent with greasy lustre
and the colour is very pale yellow to colourless in thin fragments to light yellow in aggregates
(MM 84.6.913-920).
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