Piilonenite-(Nd) mineral
Hydrated sodium-neodymium carbonate mineral with current September 2026 IMA-CNMNC approved formula NaNd(CO3)2(H2O)3 and a unique layered structure chemically analogous to the NaY(CO3)2·6H2O hexahydrate adamsite-(Y) and the Na3Y(CO3)3·3H2O trihydrate shomiokite-(Y). The primary description by Lykova et al. (2026) cites approval number IMA 2025-031, whereas the September 2026 IMA Master List (PDF p. 173) prints 2025-031b; both identifiers refer to the same Mont Saint-Hilaire holotype (CMNMC 93393, from 3-6 cm wide apophyses of the Poudrette pegmatite cutting a hornfels xenolith on level 8 of the Poudrette (Demix) quarry, previously conflated under provisional code UK119), and IMA:2025-031 is recorded as the canonical CURIE while retaining the 2025-031b suffix note from the master list. Electron-microprobe WDS analysis on holotype CMNMC 93393 (7 analyses, Table 1, p. 340) yielded Na2O 9.29, Y2O3 1.71, La2O3 0.93, Ce2O3 8.32, Pr2O3 2.75, Nd2O3 23.90, Sm2O3 6.85, Eu2O3 0.27, Gd2O3 3.64, Tb2O3 0.12, Dy2O3 0.90, Ho2O3 0.13, Er2O3 0.12, Tm2O3 0.07, CO2* 26.32, H2O* 16.16, total 101.48 wt%, corresponding to the empirical formula Na1.00(Nd0.48Ce0.17Sm0.13Gd0.07Pr0.06Y0.05La0.02Dy0.02)Sigma1.00(CO3)2(H2O)3 (with two Y-enriched zones reaching 18.43 wt% Y2O3 / 0.53 apfu Y), where CO2 and H2O were calculated by stoichiometry rather than directly measured because of the paucity of pure material. Synchrotron single-crystal X-ray diffraction at 298(2) K (ALS beamline 12.2.1, lambda = 0.7288 A, Table 3, p. 342) on an inversion-twinned crystal (54:46 ratio) refined in orthorhombic space group P212121 (a = 6.7914(11), b = 17.135(3), c = 6.4360(10) A, V = 749.0(2) A3, Z = 4, R1 = 0.092, wR2 = 0.106 for 1168 unique reflections with I > 2sigma(I) out of 1364 unique reflections), with isotropic displacement parameters retained for C2 and several O sites (O1, O4, O5, O6, O8, O9) and unlocated hydrogen positions. The mineral slowly dissolves in room-temperature aqueous HCl with effervescence (qualitative diagnostic observation, p. 339). Distinct from adamsite-(Y), shomiokite-(Y), and elemental neodymium; no criticality designation or microbial mechanism is asserted.
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Identifiers & Classification
| System | Identifier | Label |
|---|---|---|
| IMA |
IMA:2025-031
|
Piilonenite-(Nd) |
Sources & References
-
ima_2026_09: IMA-CNMNC, The New IMA List of Minerals, September 2026, PDF page 173, Piilonenite-(Nd) row: formula NaNd(CO3)2(H2O)3, status A, IMA No. 2025-031b, country Canada, reference European Journal of Mineralogy 38 (2026), 337; column definitions on PDF page 1.
https://cnmnc.units.it/files/editor/IMA_Master_List_(2026-09).pdf (accessed 2026-10-18) -
lykova_2026_piilonenite: Lykova I, Rowe R, Teat SJ, Poirier G, Barnes S (2026), Piilonenite-(Nd), NaNd(CO3)2·3H2O, a new neodymium-dominant carbonate mineral from Mont Saint-Hilaire, Quebec, Canada, European Journal of Mineralogy 38:337-345, DOI 10.5194/ejm-38-337-2026. Complete 9-page primary PDF visually inspected: occurrence, UK119 history, and holotype CMNMC 93393 pp. 337-339; FTIR and WDS chemical composition Table 1 pp. 339-340; powder and synchrotron orthorhombic P212121 single-crystal XRD Tables 2-6 pp. 341-344; inversion twinning, isotropic C/O refinement limits, and comparison with adamsite-(Y) and shomiokite-(Y) pp. 342-344.
https://ejm.copernicus.org/articles/38/337/2026/ejm-38-337-2026.pdf (accessed 2026-10-18)
Curation History
| Timestamp | Curator | Action | Summary |
|---|---|---|---|
2026-10-19T05:22:00Z |
antigravity | CREATE | Created piilonenite-(Nd) mineral record from the September 2026 IMA master list and complete 2026 primary description, preserving the IMA 2025-031 vs 2025-031b numbering note, stoichiometric CO2/H2O calculation, and synchrotron P212121 refinement limits. |
Record source: data/records/piilonenite-nd.yaml