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Petscheckite mineral

Petscheckite (IMA 1975-038) is an IMA-accepted uranium-iron-niobium-tantalum oxide mineral with IMA September 2026 Master List formula U4+Fe2+Nb2O8 and general formula U4+Fe2+(Nb,Ta)2O8 (occurring in oxidized/hydrated metamict varieties oxy-petscheckite U4+(Fe3+2/3[]1/3)(Nb,Ta)2O8 and hydroxy-petscheckite U4+(Fe3+<1/3[]>2/3)(Nb,Ta)2O7(O,OH)). Described by Mücke and Strunz (1978) from the Antsakoa I pegmatite in the Berere pegmatite field, near Tsaratanana, Madagascar, where it occurs with columbite, strüverite, monazite, ilmenite, garnet, and tourmaline, sheathed by liandratite. Table 1 (p. 942) reports a wet-chemical analysis by W. Napiontek (UO2 40.5, combined Nb2O5 + Ta2O5 = 45.99, Fe2O3 10.01, FeO 0.10, MnO 1.32, ZrO2 0.42, Al2O3 0.71, CaO 0.49, K2O 0.05, total 99.59 wt%, identified on p. 944 as heated oxy- and hydroxy-petscheckite in approximately 1:1 proportion). Metamict when unheated; trigonal/hexagonal (space group P-31m) after recrystallization at ~650 °C, with a = 6.42 Å, c = 4.02 Å, Z = 1, SGmeas = 5.0 (unheated) to 5.5 (heated, reported for petscheckite generally), Dcalc = 7.2 g/cm3 (oxy-petscheckite) and 6.6 g/cm3 (hydroxy-petscheckite), and Mohs hardness ~5 (oxy-petscheckite) to 3.5 (hydroxy-petscheckite).

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Identifiers & Classification

System Identifier Label
IMA IMA:1975-038 Petscheckite

Microbial & Biochemical Mechanisms (1)

Petscheckite other Abiotic thermal recrystallization and

Abiotic thermal recrystallization and 1000 °C disproportionation of metamict petscheckite

other

Thermal annealing of X-ray amorphous metamict oxy-petscheckite at red heat (~650 °C) restores its trigonal P-31m crystal structure (a = 6.42 Å, c = 4.02 Å, Z = 1; with specific gravity reported for petscheckite generally increasing from 5.0 unheated to 5.5 after heating), whereas heating partially hydrated hydroxy-petscheckite at 1000 °C for 24 hours dehydrates and disproportionates it into cubic uranpyrochlore U4+(Nb,Ta)2O7 (a = 10.36 Å) plus oxy-petscheckite.

Experimental Context & Analytical Limits:
Abiotic laboratory furnace annealing at red heat (~650 °C) and 24-hour calcination at 1000 °C monitored by X-ray powder diffraction; no microbial, enzymatic, or bioleaching mechanism was tested or reported in Mücke and Strunz (1978).
Curated Evidence Points:
Heating X-ray amorphous metamict oxy-petscheckite at red heat (~650 °C) restores its trigonal P-31m crystal structure (a = 6.42 Å, c = 4.02 Å, Z = 1, while general petscheckite specific gravity increases from 5.0 unheated to 5.5 after heating), whereas heating partially hydrated hydroxy-petscheckite for 24 hours at 1000 °C dehydrates and disproportionates it into cubic uranpyrochlore U4+(Nb,Ta)2O7 (a = 10.36 Å) plus oxy-petscheckite (pp. 941–945, Tables 3–4, 6).

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. 170, Petscheckite row: status A, IMA 1975-038, formula U4+Fe2+Nb2O8, reference Mücke A., Strunz H. (1978) American Mineralogist 63, 941-946.
    https://cnmnc.units.it/files/editor/IMA_Master_List_(2026-09).pdf (accessed 2026-10-24)
  2. muecke_1978_petscheckite: Mücke A and Strunz H (1978), Petscheckite and liandratite, two new pegmatite minerals from Madagascar, American Mineralogist 63:941-946.
    https://www.rruff.net/doclib/am/vol63/AM63_941.pdf (accessed 2026-10-24)

Curation History

Timestamp Curator Action Summary
2026-10-24T07:30:00Z antigravity CREATE Created mineral record for Petscheckite (IMA:1975-038) from the IMA September 2026 Master List and the primary type-description paper by Mücke and Strunz (1978) in American Mineralogist 63:941-946, including its abiotic thermal recrystallization and disproportionation mechanism.
2026-10-24T10:45:00Z antigravity EDIT Resolved CMM120-F3 (issue #838) by correcting the shifted Table 1 chemical analysis (combined Nb2O5 + Ta2O5 = 45.99, Fe2O3 10.01, FeO 0.10, MnO 1.32, ZrO2 0.42, Al2O3 0.71, CaO 0.49, K2O 0.05, total 99.59 wt% on a ~1:1 heated oxy/hydroxy mixture), qualifying the general 5.0-to-5.5 specific gravity increase and p. 945 balanced reaction stoichiometry, and simplifying sources[1].title to a concise bibliographic citation.
2026-10-24T11:27:00Z antigravity EDIT Applied reviewed conservative correction for CMM120-F3 (issue #838): omitted the unbalanced synthetic disproportionation stoichiometry from mechanisms[0] while retaining the supported ~650 °C recrystallization and 1000 °C disproportionation phases.

Record source: data/records/petscheckite.yaml