| Thomasclarkite-(Y) | |
|---|---|
| General | |
| Category | Rare earth mineral |
| Chemical formula | (Na, Ce)(Y, REE)(HCO3)(OH)3·4(H2O) |
| Identification | |
| Molar mass | 375.77 gm |
| Color | White, yellow |
| Crystal habit | Blocky crystals pseudo-tetragonal |
| Crystal system | Monoclinic - Sphenoidal H-M Symbol (2) Space Group: P 2 |
| Twinning | Common on (101) |
| Cleavage | [010] Perfect, [101] Parting |
| Fracture | Uneven |
| Tenacity | Very brittle |
| Mohs scale hardness | 2-3 |
| Luster | Vitreous (Glassy) |
| Streak | white |
| Diaphaneity | Translucent to transparent |
| Specific gravity | 2.30 |
| Optical properties | pseudouniaxial negative 2V(meas.) ≤ 5° |
| Refractive index | α= 1.40, β= 1.540, γ= 1.540 |
| Birefringence | δ = 0.140 |
| Other characteristics | Radioactivity 770 Bq/g |
| References | [1][2][3] |
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.