Khomyakovite mineral
Sodium-strontium-calcium-iron(II)-zirconium-tungsten cyclosilicate mineral of the eudialyte group with current September 2026 IMA-CNMNC approved formula Na12Sr3Ca6Fe3Zr3W(Si25O73)(O,OH,H2O)3(Cl,OH)2, status A, and approval number IMA 1998-042. Johnsen, Gault, Grice, and Ercit (1999) described the holotype specimen (CMNMC 81557, Canadian Museum of Nature, Ottawa; one of only three 0.1-0.2 mm pyramidal crystals recovered) from a 5 cm miarolitic cavity in coarse-grained nepheline syenite at the Poudrette quarry, Mont Saint-Hilaire, Rouville County, Quebec, Canada, associated with analcime, natrolite, microcline, albite, aegirine, arfvedsonite, calcite, titanite, galena, petarasite, hilairite, and catapleiite. JEOL 733 WDS electron-microprobe analysis of the structure crystal (pp. 893 and 896) with H2O calculated from crystal-structure site assignments yielded SiO2 43.70, ZrO2 10.62, HfO2 0.18, TiO2 0.11, Nb2O5 1.33, Ta2O5 0.02, WO3 3.80, Al2O3 0.09, La2O3 0.21, Ce2O3 0.18, FeO 4.33, MnO 1.63, MgO 0.04, CaO 10.42, SrO 8.45, Na2O 11.35, K2O 0.52, H2O 0.87 (calc), Cl 0.67, less O=Cl 0.15, total 98.37 wt%, corresponding on the basis of 78.70 anions (determined by single-crystal refinement) to the empirical formula (Na12.26Ca0.33K0.38Sr0.13REE0.08)Sigma13.05(Sr2.78Na0.22)Sigma3Ca6(Fe2.05Mn0.78Mg0.03)Sigma2.86(Zr2.94Ti0.05Hf0.03)Sigma3.02(W0.56Nb0.34)Sigma0.90(Si24.78Al0.06)Sigma24.84O73(O,OH,H2O)Sigma3.70(OH1.36Cl0.64)Sigma2. Single-crystal X-ray diffraction refined in acentric trigonal space group R3m (a = 14.2959(8), c = 30.084(3) A, V = 5324.6(7) A3, Z = 3, R1 = 0.049, wR2 = 0.082 for 3863 reflections with Fo > 4sigma(Fo), Dcalc = 3.14 g/cm3; uniaxial negative, omega = 1.6279(5), epsilon = 1.6254(5), Mohs hardness 5-6; Tables 1-4, pp. 894-898) demonstrated ordering of W6+ at the octahedral M(3) ring-center site, Si(7) tetrahedra at the second 9-membered ring center, Fe2+ at 4-fold planar M(2,4) and 5-fold M(2,5) sites, and Sr2+ dominant (93%) at the 9-coordinated Na(4) site. Distinct from manganokhomyakovite (the Mn-dominant analogue described in the same paper), johnsenite-(Ce), kentbrooksite, eudialyte, and elemental tungsten, strontium, zirconium, or niobium; no criticality designation, microbial mechanism, or industrial recovery yield is asserted.
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Identifiers & Classification
| System | Identifier | Label |
|---|---|---|
| IMA |
IMA:1998-042
|
Khomyakovite |
Sources & References
-
ima_2026_09: IMA-CNMNC, The New IMA List of Minerals, September 2026, PDF page 112, Khomyakovite row: formula Na12Sr3Ca6Fe3Zr3W(Si25O73)(O,OH,H2O)3(Cl,OH)2, status A, IMA No. 1998-042, country Canada, reference Canadian Mineralogist 37 (1999), 893; column definitions on PDF page 1.
https://cnmnc.units.it/files/editor/IMA_Master_List_(2026-09).pdf (accessed 2026-10-23) -
johnsen_1999_khomyakovite: Johnsen O, Gault RA, Grice JD, Ercit TS (1999), Khomyakovite and manganokhomyakovite, two new members of the eudialyte group from Mont Saint-Hilaire, Quebec, Canada, Canadian Mineralogist 37:893-899. Complete 7-page primary PDF visually inspected: Poudrette quarry occurrence, holotype CMNMC 81557, physical/optical properties, and powder XRD Table 1 pp. 893-895; WDS microprobe composition p. 896; trigonal R3m single-crystal refinement Tables 2-4 pp. 896-898.
https://www.rruff.net/doclib/cm/vol37/CM37_893.pdf (accessed 2026-10-23)
Curation History
| Timestamp | Curator | Action | Summary |
|---|---|---|---|
2026-10-23T07:15:00Z |
antigravity | CREATE | Created khomyakovite mineral record with verified IMA:1998-042 identity, Poudrette quarry holotype CMNMC 81557 WDS chemistry, and acentric trigonal R3m eudialyte-group crystal structure from the complete 1999 primary study. |
Record source: data/records/khomyakovite.yaml