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Adamsite-(Y) mineral

Hydrated sodium-yttrium carbonate mineral with current September 2026 IMA-CNMNC approved formula NaY(CO3)2(H2O)3·3H2O and approval number IMA 1999-020. Grice, Gault, Roberts, and Cooper (2000) described the cotype specimens (CMNMC 82939 and CMNMC 82940, formerly provisional phases UK 96 and UK 106) from the Poudrette dike, Poudrette quarry, Mont Saint-Hilaire, Rouville County, Quebec, Canada, where it occurs with Petersenite-(Ce), shomiokite-(Y), thomasclarkite-(Y), donnayite-(Y), and rhodochrosite. Electron-microprobe WDS analysis (7 analyses on 3 crystals, p. 1460) combined with thermogravimetric analysis yielded Na2O 8.64, CaO 0.05, Y2O3 22.88, Ce2O3 0.37, Nd2O3 1.41, Sm2O3 1.02, Gd2O3 1.92, Tb2O3 0.56, Dy2O3 3.28, Ho2O3 0.90, Er2O3 2.83, Tm2O3 0.27, Yb2O3 1.04, CO2 25.10 (12.9 wt% evolved in TGA plus 12.2 wt% ideal non-evolved), H2O 29.90, total 100.17 wt%, corresponding on the basis of 12 O atoms to the empirical formula Na1.00(Y0.72Dy0.06Er0.05Gd0.04Nd0.03Yb0.02Sm0.02Ho0.02Ce0.01Tb0.01Tm0.01)Sigma0.99C2.04H11.87O12. Single-crystal X-ray diffraction refined in triclinic space group P-1 (a = 6.2592(4), b = 13.0838(7), c = 13.2271(5) A, alpha = 91.130(1), beta = 103.554(1), gamma = 90.188(1) degrees, V = 1052.8(1) A3, Z = 4, R = 0.046, wR = 0.058 for 3338 observed reflections with |Fo| > 5sigma(Fo); powder XRD cell a = 6.262(2), b = 13.047(6), c = 13.220(5) A, alpha = 91.17(4), beta = 103.70(4), gamma = 89.99(4) degrees, V = 1049.1(5) A3) established a layered [Y(CO3)2(H2O)]- sheet structure alternating with [Na(H2O)5]+ polyhedra and unbonded interstitial H2O molecules; hydrogen positions were inferred from O...O distances rather than refined directly. Thermogravimetric analysis under dry nitrogen demonstrated two major multi-step weight-loss intervals up to 590 degrees C, and the mineral readily dissolves with strong effervescence in 10% HCl and decrepitates in acetone or alcohol. Distinct from shomiokite-(Y), thomasclarkite-(Y), piilonenite-(Nd), and elemental yttrium; no criticality designation, microbial mechanism, or industrial recovery process is asserted.

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Identifiers & Classification

System Identifier Label
IMA IMA:1999-020 Adamsite-(Y)

Microbial & Biochemical Mechanisms (1)

Adamsite-(Y) other Laboratory thermal dehydration and par

Laboratory thermal dehydration and partial decarbonation of natural adamsite-(Y)

other

Heating two powdered samples of natural adamsite-(Y) (10.196 mg and 10.847 mg) under flowing dry nitrogen produced five resolved DTG weight- loss substeps across two major intervals between 80 and 590 degrees C, losing 4.334 mg (42.5 wt%) and 4.670 mg (43.1 wt%) for an average total loss of 42.8 wt% (versus 42.2 wt% theoretical for 12 H2O + 2 CO2 per Na2Y2(CO3)4·12H2O, i.e., 6 H2O + 1 CO2 per NaY(CO3)2·6H2O). Only half of the carbonate CO2 (12.9 wt% evolved vs 12.2 wt% ideal) was released up to 1000 degrees C, leaving an unindexed heated solid residue that effervesced in HCl and was interpreted by the authors as an oxycarbonate such as YNaO(CO3).

Experimental Context & Analytical Limits:
Thermal analysis in Grice et al. (2000), pp. 1460-1461, Table 1, and Figure 2 used two powdered samples (10.196 mg and 10.847 mg) of natural Mont Saint-Hilaire adamsite-(Y) heated in a Mettler-Toledo TA8000 / TG50 thermal system with an M3 microbalance from room temperature to 1000 degrees C at 5 degrees C/min under dry nitrogen flowing at 200 mL/min. Evolved gases were not analyzed spectroscopically, and the X-ray powder diffraction pattern of the heated residue could not be matched to known phases in the ICDD database.
Curated Evidence Points:
Table 1 and Figure 2 (pp. 1460-1461) report two main weight-loss intervals subdivided into five DTG steps on the two samples (mean total loss 42.8 wt% vs 42.2 wt% calculated for Na2Y2(CO3)4·12H2O): Step 1a (80-120 degrees C, 23.0 wt% obs vs 20.0 wt% calc, -8 H2O from unbonded interstitial OW21-OW24 and weakly bonded OW17-OW20); Step 1b (120-270 degrees C, 4.0 wt% obs vs 5.0 wt% calc, -2 H2O from Na-bonded OW13 and OW15; combined 80-270 degrees C loss 27.0 wt%); Step 2a (380-480 degrees C, 2.9 wt% obs vs 5.0 wt% calc, -2 H2O from Y- and Na-bridging OW14 and OW16); Step 2b (480-540 degrees C, 7.0 wt% obs vs 6.1 wt% calc, -1 CO2); and Step 2c (540-590 degrees C, 5.9 wt% obs vs 6.1 wt% calc, -1 CO2; combined 380-590 degrees C loss 15.8 wt%, including 12.9 wt% evolved CO2).
Because half of the carbonate remained in the solid residue above 590 degrees C (which effervesced in HCl and gave an unindexed XRD pattern), the second 12.2 wt% CO2 required for complete NaY(CO3)2·6H2O stoichiometry was added theoretically rather than evolved during TGA, and the structural assignment of specific OW13-OW24 water sites to individual DTG steps is an interpretive correlation.

Sources & References

  1. ima_2026_09: IMA-CNMNC, The New IMA List of Minerals, September 2026, PDF page 3, Adamsite-(Y) row: formula NaY(CO3)2(H2O)3·3H2O, status A, IMA No. 1999-020, country Canada, reference Canadian Mineralogist 38 (2000), 1457; column definitions on PDF page 1.
    https://cnmnc.units.it/files/editor/IMA_Master_List_(2026-09).pdf (accessed 2026-10-18)
  2. grice_2000_adamsite: Grice JD, Gault RA, Roberts AC, Cooper MA (2000), Adamsite-(Y), a new sodium-yttrium carbonate mineral species from Mont Saint-Hilaire, Quebec, Canadian Mineralogist 38:1457-1466, DOI 10.2113/gscanmin.38.6.1457. Complete 10-page primary PDF visually inspected: occurrence, cotypes CMNMC 82939 and CMNMC 82940, and physical properties pp. 1457-1460; WDS chemical composition and TGA/DTG thermal analysis Table 1 and Figure 2 pp. 1460-1461; XRPD Table 2 pp. 1461-1462; single-crystal triclinic P-1 structure refinement Tables 3-5 and Figures 3-5 pp. 1462-1465.
    https://www.rruff.net/doclib/cm/vol38/CM38_1457.pdf (accessed 2026-10-18)

Curation History

Timestamp Curator Action Summary
2026-10-19T05:22:00Z antigravity CREATE Created adamsite-(Y) mineral record with verified IMA identity, triclinic crystal-structure characterization, and bounded laboratory TGA/DTG thermal dehydration and partial decarbonation mechanism from the complete 2000 primary study.

Record source: data/records/adamsite-y.yaml