Category Carbonate mineral Crystal system Monoclinic | Dana classification 16b.2.4.1 | |
Formula
(repeating unit) (Y,REE)8(UO2)16(CO3)16O8(OH)8•39H2O Strunz classification 5.EB.20 (10 ed)
5/F.06-30 (8 ed) Crystal class Spheroidal (2)
(same H-M symbol) | ||
Bijvoetite-(Y) is a very rare rare earth and uranium mineral with the formula (Y,REE)8(UO2)16(CO3)16O8(OH)8•39H2O. When compared to the original description, the formula of bijvoetite-(Y) was changed in curse of crystal structure redefinition. Bijvoetite-(Y) is an example of natural salts containing both uranium and yttrium, the other examples being kamotoite-(Y) and sejkoraite-(Y). 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).
Contents
Occurrence and association
Bijvoetite-(Y) was found in Shinkolobwe dolomite-hosted uranium deposit, Rep. of Congo, where it occurs in an oxidation zone, together with numerous other uranium minerals: lepersonnite-(Gd), becquerelite, curite, kasolite, oursinite, rutherfordine, schoepite, sklodowskite, soddyite, studtite, torbernite, and uranophane.
Crystal structure
Although originally though to be orthorhombic, bijvoetite-(Y) was later shown to be monoclinic. The structural formula of the mineral is [M3+83+(H2O)25(UO2)16O8(OH)8(CO3)16](H2O)14, where M = (Y,REE). The structure has 16 uranium sites, with uranium belonging to near-linear uranyl groups. The important features of the structure are: