A nomenclature and classification scheme for wöhlerite-group minerals has been established. The general formula of minerals belonging to this group is given by X₈(Si₂O₇)₂W₄, where X = Na⁺, Ca²⁺, Mn²⁺, Ti⁴⁺, Zr⁴⁺ and Nb⁵⁺; and W = F^– and O^2–. In addition, they may incorporate significant amounts of Mg²⁺, Fe²⁺, Y³⁺ and REE³⁺, where REE are the lanthanides. The main structural feature of these minerals is the four-columns-wide octahedral walls, which are interconnected through corner sharing and via the disilicate groups. The wöhlerite-group minerals crystallise in different unit-cell settings and symmetries, depending on the cationic ordering in the octahedral walls and the relative position of the disilicate groups. Different combinations of X and W constituents should be regarded as separate mineral species. In the case of coupled heterovalent substitutions at different crystallographic sites, it is advised to use the site-total charge approach to determine the correct end-member composition. Due to their structural and chemical features, wöhlerite-group minerals can easily form crystals with several micro domains, showing different crystal structures and chemical compositions. In addition, the crystallisation of polytypes is relatively common, although they should not be regarded as distinct mineral species. To date, ten minerals belonging to the wöhlerite group are considered as valid species: baghdadite, burpalite, cuspidine, hiortdahlite, janhaugite, låvenite, moxuanxueite, niocalite, normandite and wöhlerite. Låvenite and normandite are isostructural and are respectively the Zr and Ti end-members of a solid-solution series. Marianoite is discredited, as it is corresponds to wöhlerite. The ideal formula of hiortdahlite is revised as Na₂Ca₄(Ca_0.5Zr_0.5)Zr(Si₂O₇)₂OF₃, with one cationic site characterised by a valency-imposed double site-occupancy. These changes have been approved by the IMA–CNMNC (Proposal 20–D).

Paddlewheelite, MgCa₅Cu₂[(UO₂)(CO₃)₃]₄·33H₂O, is a new uranyl carbonate mineral found underground in the Svornost mine, Jáchymov District, Bohemia, Czech Republic, where it occurs as a secondary oxidation product of uraninite. The conditions leading to its crystallization are complex, likely requiring concomitant dissolution of uraninite, calcite, dolomite, chalcopyrite, and andersonite. Paddlewheelite is named after its distinctive structure, which consists of paddle-wheel clusters of uranyl tricarbonate units bound by square pyramidal copper “axles” and a cubic calcium cation “gearbox.” Paddle wheels share edges with calcium polyhedra to form open sheets that are held together solely by hydrogen bonding interactions. The new mineral is monoclinic, Pc, a = 22.052(4), b = 17.118(3), c = 19.354(3) Å, β = 90.474(2)°, V = 7306(2) ų and Z = 4. Paddlewheelite is the second-most structurally complex uranyl carbonate mineral known after ewingite and its structure may provide insights into the insufficiently described mineral voglite, as well as Cu–U–CO₃ equilibrium in general.

A carbonate-bearing, fluorine-overcompensated fluorapatite (F = 4.42 wt.% as compared with 3.77 wt.% F in the Ca₅(PO₄)₃F end-member), was identified in forsterite-bearing skarns from Valea Rea (N 46°39′48″, E 22°36′43″), located near the contact of the granodiorite laccolith from Budureasa, of Upper Cretaceous Age, with Anisian dolostones. The chemical structural formula (with carbonate not included) is: (Ca_4.989Mn_0.001Fe²⁺_0.003Mg_0.003Ce_0.001La_0.001)(P_2.992Si_0.008)(O_11.894F_1.202Cl_0.001). No major structural distortions due to (CO₃F)^3--for-(PO₄)^3- replacement were identified by single crystal X-ray diffraction, Raman or FTIR. The mineral crystallizes in space group P6₃/m, having as cell parameters a = 9.3818(1) Å and c = 6.8872(1) Å. The indices of refraction are: ω = 1.634(2) and ε = 1.631(1). The calculated density is D_x = 3.199 g/cm³ and the measured density is D_m = 3.201(3) g/cm³. Calculation of the Gladstone–Dale compatibility indices gave in all cases values indicative of superior agreement between physical and chemical data. In the infrared spectra, the multiplicity of the bands assumed to phosphate modes (1ν₁ + 2ν₂ + 3ν₃ + 3ν₄) agrees with the reduction of the symmetry of PO₄³⁻ ion from T_d to C₆. Chemical peculiarities and textural relations agree with a hydrothermal origin of the mineral, crystallized from F-rich fluids originating from the granodiorite intrusion.