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Montroseite mineral

Montroseite is the vanadium oxyhydroxide mineral with ideal formula V3+O(OH), listed as grandfathered (G), original-description year 1953, in the September 2026 IMA list. That year is not a numbered IMA approval. The original Colorado Plateau specimens were iron-bearing, commonly altered and incompletely separated from associated minerals. Single-crystal diffraction assigned the sharp orthorhombic Pbnm lattice to montroseite; the diffuse lattices and much of the original bulk powder pattern represent altered material, subsequently distinguished as paramontroseite or unresolved diffuse A. The historical Fe2+/V4+ compensation model is a chemical interpretation, not a modern site-specific valence measurement. Montroseite is distinct from paramontroseite, elemental vanadium and mixed uranium-vanadium ore. The cited natural evidence does not establish microbial formation, extraction, isolated-product recovery or industrial deployment; criticality is not inherited from vanadium.

Microbial & Biochemical Mechanisms (1)

Inferred oxidation and hydrogen loss during natural weathering

redox transformation

Evans and Mrose interpreted natural montroseite-paramontroseite intergrowths as oxidation of VO(OH) to orthorhombic VO2 with hydrogen loss while retaining a related oxygen framework. Their proposed reaction is 2VO(OH) + 0.5O2 -> 2VO2 + H2O. This is a structural and geological inference from altered natural crystals, not a controlled conversion experiment or measured hydrogen-transport mechanism.

Experimental Context & Analytical Limits:
The Bitter Creek mine, Paradox Valley, Colorado, supplied two altered crystals. One contained sharp montroseite plus diffuse paramontroseite and a weaker unresolved diffuse-A phase; the other gave nearly pure paramontroseite diffraction with slight residual montroseite reflections. The 1955 study reused the 1953 montroseite intensity data, so the papers and the two mineral records do not represent independent replications. The proposed below-50-degrees-C atmospheric or groundwater weathering setting has no measured reaction duration, pH, oxygen activity, conversion fraction or matched laboratory control. Diffuse A could be an intermediate or a separated Fe-rich phase; its identity was unresolved.
Curated Evidence Points:
Pages 863 and 867 distinguish the two natural crystals, visually estimated 99 montroseite and 34 paramontroseite reflections, no absorption correction, and poorer diffuse-phase data. Figures 1-4 and Table 4 show related, parallel lattices and an interoxygen separation interpreted as a hydrogen bond in montroseite but not paramontroseite. Pages 872-874 infer oxidation and hydrogen migration; they do not directly track atoms or establish a universal low-temperature rate or equilibrium boundary.
Context_only Source: weeks1953
Pages 1239-1241 and Tables 2-3 show that bulk powder patterns and chemical analyses include altered and impure material. The Matchless composition was calculated as about 35 percent substituted oxyhydroxide and 65 percent VO2, not measured conversion in a timed assay. Bitter Creek, Matchless and Whitney separates have different impurities and must not be pooled as pure montroseite or paramontroseite.

Sources & References

  1. ima_2026_09: IMA-CNMNC. The New IMA List of Minerals, September 2026. Montroseite row, PDF page 147: V3+O(OH), G, 1953; status and original-description-year definitions page 1.
    https://cnmnc.units.it/files/editor/IMA_Master_List_(2026-09).pdf (accessed 2026-10-15)
  2. weeks1953: Weeks AD, Cisney EA, Sherwood AM (1953). Montroseite, a new vanadium oxide from the Colorado Plateaus. American Mineralogist 38:1235-1241. Original natural description; specimens and separation pages 1236-1238; altered powder pattern page 1239; bulk chemistry, impurity and phase-mixture interpretation pages 1240-1241, Tables 2-3.
    https://msaweb.org/AmMin/AM38/AM38_1235.pdf (accessed 2026-10-15)
  3. evans_block1953: Evans HT Jr, Block S (1953). The crystal structure of montroseite, a vanadium member of the diaspore group. American Mineralogist 38:1242-1250. Single-crystal sharp versus diffuse lattices, Table 1; chemical constitution page 1249. Calculated k-odd structure factors and reported R are corrected by Evans and Mrose (1955), page 867.
    https://msaweb.org/AmMin/AM38/AM38_1242.pdf (accessed 2026-10-15)
  4. evans_mrose1955: Evans HT Jr, Mrose ME (1955). A crystal chemical study of montroseite and paramontroseite. American Mineralogist 40:861-875. Bitter Creek crystals and shared 1953 data page 863; correction page 867; Tables 1-5, Figures 1-4; inferred solid-state alteration pages 872-874.
    https://msaweb.org/AmMin/AM40/AM40_861.pdf (accessed 2026-10-15)

Curation History

Timestamp Curator Action Summary
2026-10-15T19:31:42.446363Z codex (GPT-6; codex) CREATE Prepared primary-evidence mineral identity and qualified abiotic transformation, retaining natural intergrowths, shared study dependence, historical corrections and specimen-specific measurement limits.

Record source: data/records/montroseite.yaml