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CMMMech > Mineral > Virgilite

Virgilite mineral

Virgilite (IMA 1977-009) is an IMA-accepted lithium aluminosilicate framework mineral with a stuffed beta-quartz structure, with IMA September 2026 Master List formula LiAlSi2O6 and holotype solid-solution composition Li0.61(Si2.37Al0.60Fe0.02P0.01)O6 (approximately 61 mol% LiAlSi2O6 and 39 mol% SiO2; Table 1, p. 463 holotype NMNH 2143-17 electron microprobe oxides SiO2 77.29, Al2O3 16.57, FeO 0.64, P2O5 0.57 wt% with Li2O = 4.93 wt% calculated by difference, total 100.0 wt%, supported by ~5 wt% Li2O from laser spectrographic analysis of sample 2143-3). Described by French, Jezek, and Appleman (1978) from the Macusani peraluminous rhyolitic volcanic glass (14°S, 70°30'W), Carabaya Province, Puno Department, southeastern Peru (holotype NMNH 2143-17), where it occurs as colorless euhedral microphenocrysts (up to 50 um across, plus fibrous rosette-like overgrowths) with quartz, andalusite, sillimanite, and biotite. Hexagonal (space group P6222 or P6422), with a = 5.132(1) Å, c = 5.454(1) Å, V = 124.41(2) Å3, Z = 1, Dcalc = 2.46 g/cm3, Vickers microhardness VHN = 681–722 kg/mm2, and uniaxial (–) optics with n = 1.520 and birefringence 0.005–0.006.

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Identifiers & Classification

System Identifier Label
IMA IMA:1977-009 Virgilite

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. 229, Virgilite row: status A, IMA 1977-009, formula LiAlSi2O6, reference French B.M., Jezek P.A., Appleman D.E. (1978) American Mineralogist 63, 461-465.
    https://cnmnc.units.it/files/editor/IMA_Master_List_(2026-09).pdf (accessed 2026-10-24)
  2. french_1978_virgilite: French BM, Jezek PA, and Appleman DE (1978), Virgilite, a new lithium aluminum silicate mineral from the Macusani glass, Peru, American Mineralogist 63:461-465.
    https://www.rruff.net/doclib/am/vol63/AM63_461.pdf (accessed 2026-10-24)

Curation History

Timestamp Curator Action Summary
2026-10-24T07:30:00Z antigravity CREATE Created mineral record for Virgilite (IMA:1977-009) from the IMA September 2026 Master List and the primary type-description paper by French, Jezek, and Appleman (1978) in American Mineralogist 63:461-465.
2026-10-24T10:45:00Z antigravity EDIT Resolved CMM120-F14 (issue #838) by distinguishing Table 1 electron microprobe oxides from Li2O = 4.93 wt% calculated by difference (and ~5 wt% Li2O by laser spectrograph on sample 2143-3), correcting euhedral microphenocryst size to up to 50 um across (plus fibrous rosette overgrowths), and simplifying sources[1].title to a concise bibliographic citation.
2026-10-24T11:27:00Z antigravity EDIT Applied reviewed conservative correction for CMM120-F14 (issue #838): removed unsupported qualitative ion-microprobe Li claim and unsupported muscovite association from description while retaining the verified Table 1 assay and sample 2143-3 laser-spectrographic Li2O.

Record source: data/records/virgilite.yaml