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Lucasite-(Ce) mineral

Lucasite-(Ce) (IMA 1986-020) is an IMA-accepted cerium-titanium oxide-hydroxide mineral with IMA September 2026 Master List formula CeTi2O5(OH) and crystal-chemical formula CeTi2(O,OH)6 (empirical formula Ce0.51La0.27Nd0.11Pr0.11Ti2(O,OH)6). Described by Nickel, Grey, and Madsen (1987) from heavy-mineral concentrates of the Argyle AK1 diamondiferous olivine lamproite tuff, East Kimberley region, Western Australia, Australia. Table 1 (p. 1007) reports the mean of eight electron-microprobe analyses: Ce2O3 24.99, La2O3 13.12, Nd2O3 5.90, Pr2O3 5.50, CaO 0.62, TiO2 47.93, MgO 0.03, SiO2 0.25, Al2O3 0.04, total 98.38 wt% (with F not analyzed and the low 98.38 wt% total together with bond-valence sums interpreted as indicating hydroxyl/water substitution). Monoclinic (space group I2/a, equivalent to standard C2/c; refined to R = 0.054 for 977 independent reflections), with a = 5.178(1) Å, b = 8.756(4) Å, c = 9.768(5) Å, beta = 93.52(4)°, Z = 4, Dcalc = 5.00 g/cm3, Vickers microhardness VHN10 = 761–900 kg/mm2 (mean 824 kg/mm2), {001} cleavage, and refractive indices n > 2.0 (Gladstone-Dale calculated mean n = 2.321).

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Identifiers & Classification

System Identifier Label
IMA IMA:1986-020 Lucasite-(Ce)

Sources & References

  1. ima_2026_09: IMA-CNMNC (Pasero M., 2026), The New IMA List of Minerals – A Work in Progress (Updated: September 2026), PDF p. 128, Lucasite-(Ce) row: status A, IMA 1986-020, formula CeTi2O5(OH), reference Nickel E.H., Grey I.E., Madsen I.C. (1987) American Mineralogist 72, 1006-1010.
    https://cnmnc.units.it/files/editor/IMA_Master_List_(2026-09).pdf (accessed 2026-10-24)
  2. nickel_1987_lucasite_ce: Nickel EH, Grey IE, and Madsen IC (1987), Lucasite-(Ce), CeTi2(O,OH)6, a new mineral from Western Australia: Its description and structure, American Mineralogist 72:1006-1010.
    https://www.rruff.net/doclib/am/vol72/AM72_1006.pdf (accessed 2026-10-24)

Curation History

Timestamp Curator Action Summary
2026-10-24T07:30:00Z antigravity CREATE Created mineral record for Lucasite-(Ce) (IMA:1986-020) from the IMA September 2026 Master List and the primary type-description paper by Nickel, Grey, and Madsen (1987) in American Mineralogist 72:1006-1010.
2026-10-24T10:45:00Z antigravity EDIT Resolved CMM120-F10 (issue #838) by replacing the unsupported expanded chemical list and Pr2O3 typo claim with the actual Table 1 (p. 1007) 8-analysis mean (Pr2O3 5.50, CaO 0.62, total 98.38 wt% with hydroxyl inferred from the low total and bond-valence sums) and simplifying sources[1].title to a concise bibliographic citation.
2026-10-24T11:27:00Z antigravity EDIT Applied reviewed conservative correction for CMM120-F10 (issue #838): omitted two-grain attribution in description and retained the verified Table 1 (p. 1007) eight-analysis mean.

Record source: data/records/lucasite-ce.yaml