Thomasclarkite
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Thomasclarkite-(Y) | |
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Category | Mineral |
Chemical formula | (Na,Ce)(Y,REE)(HCO3)(OH)3·4(H2O) |
Identification | |
Molecular Weight | 375.77 gm |
Color | White, Yellow |
Crystal habit | Blocky crystals pseudo-tetragonal |
Crystal system | Monoclinic - Sphenoidal |
Twinning | Common on (101) |
Cleavage | [010] Perfect, [101] Parting |
Fracture | Brittle - Uneven - Very brittle fracture producing uneven fragments |
Mohs Scale hardness | 2-3 |
Luster | Vitreous (Glassy) |
Refractive index | α= 1.40, β= 1.540, γ= 1.540 |
Optical Properties | pseudouniaxial negative 2V(meas.) = 5° |
Birefringence | δ = 0.140 |
Streak | white |
Specific gravity | 2.30 |
Diaphaneity | Translucent to transparent |
Other Characteristics | Radioactivity 770 Bq/g |
Thomasclarkite-(Y) is a very rare mineral which was known as UK-93 until 1997, when it was renamed in honour of Dr. Thomas H. Clark (1893-1996), McGill University professor. The mineral is one of many rare earth element minerals from Mont Saint-Hilaire. Rare occurrence in an alkalic pegmatite dike in an intrusive gabbro-nepheline syenite.