Bijvoetite-(Y)
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5/F.06-30 (8 ed)
| Bijvoetite-(Y) | |
|---|---|
| General | |
| Category | Carbonate mineral |
| Formula | (Y,REE)8(UO2)16(CO3)16O8(OH)8•39H2O |
| IMA symbol | Bij-Y[1] |
| Strunz classification | 5.EB.20 (10 ed) 5/F.06-30 (8 ed) |
| Dana classification | 16b.2.4.1 |
| Crystal system | Monoclinic |
| Crystal class | Spheroidal (2) (same H-M symbol) |
| Space group | B21 |
| Unit cell | a = 21.23, b = 12.96, c = 44.91 [Å], β = 90.00° (approximated); Z = 4 |
| Identification | |
| Color | Yellow |
| Crystal habit | Plates |
| Cleavage | {001}, good |
| Mohs scale hardness | 2 |
| Luster | Vitreous |
| Streak | Light yellow |
| Diaphaneity | Transparent to translucent |
| Density | 3.97 (measured) |
| Optical properties | Biaxal (+) |
| Refractive index | nα = 1.60, nβ = 1.65, nγ = 1.72 (approximated) |
| Pleochroism | Colorless (X), pale yellow (Y), deep yellow (Z) |
| 2V angle | 84° (measured) |
| Other characteristics |  Radioactive |
| References | [2][3][4][5] |
Bijvoetite-(Y) is a very rare rare-earth and uranium mineral[3][4] with the formula (Y,REE)8(UO2)16(CO3)16O8(OH)8·39H2O.[4][5] When compared to the original description, the formula of bijvoetite-(Y) was changed in the course of crystal structure redefinition.[2] Bijvoetite-(Y) is an example of natural salts containing both uranium and yttrium, the other examples being kamotoite-(Y) and sejkoraite-(Y).[6][7] Bijvoetite-(Y) comes from Shinkolobwe deposit in Republic of Congo, which is famous for rare uranium minerals. The other interesting rare-earth-bearing uranium mineral, associated with bijvoetite-(Y), is lepersonnite-(Gd).[3]
The mineral is named after the Dutch chemist and crystallographer Johannes Martin Bijvoet.
Other rare-earth elements substituting for yttrium ("REE" in the given formula) are mainly neodymium, samarium, gadolinium, and dysprosium, with minor cerium, europium, terbium and erbium.[2] This is in slight opposition to the original reported analysis, that had dysprosium, gadolinium and terbium as main substituting REE.[4]