Thomasclarkite-(Y) Locality: Poudrette quarry (Demix quarry; Uni-Mix quarry; Desourdy quarry), Mont Saint-Hilaire , Rouville RCM, Montérégie , Québec , Canada ( Locality at mindat.org ) Field of view 4 mm. Specimen and photo Leon Hupperichs. — Photo: Leon Hupperichs · CC BY-SA 3.0
Thomasclarkite-(Y)
Thomasclarkite-(Y) is a rare mineral which was known as UK-93 until 1997, when it was renamed in honour of Thomas H. Clark (1893–1996), McGill University professor. The mineral is one of many rare-earth element minerals from Mont Saint-Hilaire. The only reported occurrence is in an alkalic pegmatite dike in an intrusive gabbro-nepheline syenite.
Intro adapted from Wikipedia (CC BY-SA).
Thomasclarkite-(Y) is an IMA-recognized mineral species in the carbonate class, with the chemical formula NaY(HCO₃)(OH)₃·4H₂O.
It crystallizes in the monoclinic crystal system (space group P2).
Key properties: Mohs hardness 2–3; specific gravity 2.3; White streak; Vitreous luster; optically biaxial.
IMA symbol Tcl-Y, IMA status: approved, named in 1997.
Rarely in a pegmatite dike in association with an intrusive alkalic gabbro-syenite complex.
It is found associated with Aegirine, albite, analcime, ancylite-(Ce), astrophyllite, calcite, catapleiite, dawsonite, elpidite, epididymite, franconite, gaidonnayite, galena.
The mineral was named to honor Professor Thomas Henry Clark (1893–1996), McGill University, Montreal, Canada, who studied the geology of the area in which Mont Saint-Hilaire is situated.