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.

Thomasclarkite-(Y)
General
CategoryCarbonate mineral
Formula
(repeating unit)
(Na, Ce)(Y, REE)(HCO3)(OH)3·4(H2O)
Crystal systemMonoclinic
Crystal classSphenoidal (2)
(same H-M symbol)
Space groupP2
Identification
Formula mass375.77 g/mol
ColorWhite, yellow
Crystal habitBlocky crystals, pseudo-tetragonal
TwinningCommon on (101)
Cleavage[010] perfect, [101] parting
FractureUneven
TenacityVery brittle
Mohs scale hardness2–3
LusterVitreous (Glassy)
Streakwhite
DiaphaneityTranslucent to transparent
Specific gravity2.30
Optical propertiespseudouniaxial negative 2V (meas.) ≤ 5°
Refractive indexnα = 1.40, nβ = 1.540, nγ = 1.540
Birefringenceδ = 0.140
Other characteristics Radioactive 770 Bq/g
References[1][2][3]

See also

References

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