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Paramontroseite mineral

Paramontroseite is the orthorhombic vanadium dioxide mineral, ideal VO2, listed as grandfathered (G), original-description year 1955, in the September 2026 IMA list. The year is not a numbered IMA approval. It is structurally distinct from generic VO2 and rutile-type or monoclinic VO2 phases, and chemically distinct from montroseite VO(OH). Evans and Mrose established the natural diffuse-B phase in altered Bitter Creek montroseite crystals using a Pbnm model. The inferred natural weathering relation is distinct from the later laboratory heating of Fe-rich Prachovice paramontroseite. The 2023 specimen is zoned, Al-bearing and nonideal; its refinement favors Fe in a separate tetrahedral site and cannot be substituted for a pure-VO2 endmember or a measurement on the 1950s Colorado specimen. Criticality is not inherited from vanadium, and the curated studies establish no microbial mechanism or industrial recovery.

Microbial & Biochemical Mechanisms (2)

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.

Heating-associated oxidative breakdown of Fe-bearing natural paramontroseite

redox transformation

Curetti and Pavese observed Fe-bearing natural paramontroseite progressively break down into diffraction-assigned V2O5 and Fe2V4O13 during laboratory heating. Under their stepped powder protocol, new phases appeared in the 350-400 degrees C interval, and Figure 7 retains parent paramontroseite at 400 and 450 degrees C but not in its plotted 500 degrees C assemblage. This supports specimen-specific oxidative phase transformation, not vanadium extraction, product recovery or a universal transition temperature for pure VO2.

Experimental Context & Analytical Limits:
The Prachovice, Czech Republic, specimen contains compositionally zoned Fe/Al-bearing paramontroseite on a calcite matrix with associated U-rich material. Crystals selected from U-free mapped areas for powder diffraction still contained about 8 weight percent calcite. The powder was placed in a flat Pt holder, heated at 20 degrees C per minute, and measured at 50-degree intervals up to a stated 550 degrees C after 2-hour holds; each diffraction scan took about 150 minutes. Figure 7 ends at 500 degrees C and the cell-parameter table at 450 degrees C. The gas composition/flow and oxygen fugacity are not specified. Separate crystals heated for 6 hours at 400 degrees C were used for EDS and Raman work; those results are not an identical powder time series. There is no pure-VO2 matched comparison, measured dissolved vanadium, isolated-product mass balance or demonstrated industrial process.
Curated Evidence Points:
Sections 2.1-2.5, Figures 1-3 and 5-7 and Table 3 establish the natural feed, selected powder with calcite, temperature protocol and mixed diffraction products. Section 3.2 identifies V2O5 and Fe2V4O13 and infers oxidation of V4+ to V5+ from the assigned phases. Parent diffraction persists through 450 degrees C in Table 3 and Figure 7. The transformation did not yield an observed rutile-type VO2 phase under this protocol.
Section 3.2 reports final Fe2V4O13 and V2O5 proportions of about 65 and 35 weight percent respectively, but the labeled stacked bars in Figure 7 show V2O5 as the larger final product and retain calcite. The exact product fractions and denominator therefore remain unresolved and are not treated as recovery yields. The proposed balanced reaction uses an approximate Al-free V0.8Fe0.2O2 formula, distinct from both the measured average composition and refined occupancies. Absence of an amorphous intermediate is inferred from retained calcite fraction, not a separately quantified glass assay.
Sections 2.2-2.3 and 3.1, Tables 1-2 and Figure 4 favor Fe in a separate tetrahedral site for this Fe-rich specimen, rather than simple V-site substitution. The average chemical formula V0.84Fe0.19Al0.03O2 differs from refined site occupancies, and small Al is omitted in the proposed model; EDS and refinement do not directly measure every cation valence. Section 3.3 and Figure 9 show laser-induced changes and overlapping Raman peaks; an Fe2V4O13 reference spectrum was unavailable, so individual Raman assignments are not unique and a database match is not an unaltered-paramontroseite fingerprint.

Sources & References

  1. ima_2026_09: IMA-CNMNC. The New IMA List of Minerals, September 2026. Paramontroseite row, PDF page 165: VO2, G, 1955; 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_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)
  4. curetti2023: Curetti N, Pavese A (2023). Fe-bearing vanadium dioxide-paramontroseite: structural details and high-temperature transformation. European Journal of Mineralogy 35:373-382. DOI 10.5194/ejm-35-373-2023. Natural Prachovice specimen and separate heating protocols sections 2.1-2.5; Tables 1-4 and Figures 1-9; transformation and unresolved product proportions section 3.2/Figure 7; Raman limitations section 3.3. Full original and publisher table workbooks inspected.
    https://doi.org/10.5194/ejm-35-373-2023 (accessed 2026-10-15)

Curation History

Timestamp Curator Action Summary
2026-10-15T19:31:42.455790Z 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/paramontroseite.yaml