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Formula: NaCaCeF6
Fluoride, cerium-bearing mineral
Crystal System: Trigonal
Specific gravity: 4.44 measured
Hardness: 3½
Streak: White
Colour: Colourless to light pink, colourless in transmitted light
Luminescence: Not fluorescent in shortwave or long wave UV
Solubility: Insoluble in water, unreactive in cold, dilute hydrochloric acid, slowly dissolved by hot hydrochloric
acid
Environments
Gargarinite-(Ce) was first published as zajacite-(Ce) in 1996, renamed in 2010 and to date (March 2024)
reported only from the type locality
Localities
The type locality, the Strange Lake complex, Canada, straddles the Quebec-Newfoundland and Labrador border. It
occurs within a Precambrian (4,600 to 541 million years ago) peralkaline (aluminium-deficient)
granitic complex. The host
granite consists largely of
quartz, perthite and
arfvedsonite.
Gargarinite-(Ce) occurs sparingly as xenomorphic grains, typically 1.5 to 2 mm across, that are disseminated
within the granite, which also contains accessory
vlasovite, narsarsukite,
willemite and fluorite. There
are no indications of a precursor phase, and gargarinite-(Ce) is interpreted to be a
primary mineral. Inclusions of gagarinite-(Ce) have
been reported to occur with associated inclusions of zircon and
monazite within arfvedsonitic
amphibole in granite.
Fresh grains of gargarinite-(Ce) are colourless to pale pink and complelely homogeneous. In the specimens
examined, however, most of the grains have been veined by
bastnäsite-(Ce), with variably minor to extensive replacement. The
colour of gargarinite-(Ce) becomes pinkish, then more orange as the degree of alteration by heterogeneous
mixtures containing bastnäsite-(Ce) increases
(CM 34.6.1299-1304 as zajacite-(Ce), renamed in 2010).
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