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Anhydrite mineral

Anhydrite is the grandfathered calcium sulfate mineral species CaSO4, distinct from gypsum, bassanite, elemental calcium or sulfur, and mixed industrial residues such as phosphogypsum and titanogypsum. This owner describes the anhydrous proposed product in a disputed microbial gypsum-dehydration experiment, not a proven biologically recovered product. The same primary experiments are cross-represented in cmmmech:gypsum; their occurrence in two mineral owners does not create independent replication. Mineral identity is established separately from the contested mechanism. No constituent criticality, industrial deployment or recovery yield is asserted.

Microbial & Biochemical Mechanisms (2)

Disputed culture-associated gypsum to anhydrite transformation

other Microbial

Associated Organisms: Chroococcidiopsis (NCBITaxon:54298)

Huang2020 interpreted diffraction and microscopy of cyanobacteria-exposed gypsum as gypsum dissolution followed by anhydrite precipitation, proposing that microorganisms obtain structural water. The microbial flag identifies the culture exposure; it does not establish this disputed causal mechanism, direct cellular uptake of lattice water, exclusive action by Chroococcidiopsis, or a mineral recovery process. The gypsum and anhydrite records describe the substrate and proposed product of the same experiment, not independent demonstrations.

Experimental Context & Analytical Limits:
Huang2020 Methods, Cyanobacterial Isolation and Culture, used source-designated G-MTQ-3P2 isolated from colonized Atacama gypsum through BG11 cultivation and colony transfer. Mineral coupons were autoclaved for 20 minutes at 121 degrees C and exposed to 100 microliters of BG11 culture at 10^5 or 10^8 cells/mL. The corrected coupon dimensions are 5 by 8 by 0.5 mm, not the smaller dimensions printed in the original article. Incubation was 30 days at 25 degrees C under 24 micromol photons/m2/s white light or darkness. Dry conditions meant no additional medium after inoculation; wet conditions received periodic BG11 to maintain a thin liquid layer. Uninoculated sterile-BG11 controls were specified. Methods state that one sample per condition was ground for XRD; an independent replicate structure is not established. Figure 3E does not separately label the light versus dark arm, so its patterns are not assigned to both lighting conditions. These are laboratory exposures of selected mineral coupons, not a quantitative field water budget.
Curated Evidence Points:
Context_only Source: ima_2026_09
The IMA September 2026 list gives Anhydrite as a grandfathered mineral species with formula CaSO4. This is a mineral identity assessment, not certification of the experimental product or a criticality designation.
The Handbook independently describes the orthorhombic anhydrous calcium sulfate mineral and its powder diffraction. Geological occurrence does not establish a microbial formation pathway.
Results and original Figures 2-3 compare natural colonized material and cultured coupons. Figure 3E marks reflections assigned to anhydrite in dry low- and high-cell-density treatments while gypsum persists; wet-treatment patterns retain gypsum. The authors state that the uninoculated sample lacked anhydrite. However, a black square also appears inside the No microbe panel, while the caption defines squares as anhydrite. Its placement does not unambiguously identify a resolved peak; the inconsistency is retained without declaring control-phase presence or a clean causal contrast. Figure 3F-I provides organic/spectral context, not a measured transfer of structural water into cells. No calibrated phase fraction, analytical phase detection limit, isolated product mass or recovery yield is reported.
The formal correction replaces the two erroneous coupon-dimension statements with 5 mm by 8 mm by 0.5 mm. This resolves the published size error; it does not resolve the separate phase-assignment, control-annotation or water-uptake questions.
The two-page critique, Figure 1 and Table 1 dispute microbial causality and the interpretation of electron diffraction, and show natural gypsum/anhydrite associations and nonexclusive cell attachment. Natural co-occurrence cannot establish biological transformation. The critique also objected to dissolution of the originally printed tiny coupons; the subsequent size correction means that specific dimensional objection is not retained as an unresolved error. The remaining chemical and diffraction objections are attributed scientific disagreement, not a proof that all biological dehydration is impossible.
The reply concerns the same 2020 experiment. Its Figures 1-2 defend the electron-diffraction indexing, report selection of initially gypsum-only regions by XRD and show remaining coupons with corrected dimensions. The authors propose that hydrated biofilm permits dissolution. This is supporting clarification of their interpretation, not independent replication or a direct measurement of water uptake. The main Figure 3E control-symbol ambiguity is not explicitly resolved by the acquired reply.
Context_only Source: murray2021
The Announcement explicitly describes non-purified cyanobacterial cultures with heterotrophic companions, and Table 1 includes G-MTQ-3P2. Its reported Chroococcidiopsis MAG does not establish an axenic stock or identify the organism exclusively responsible for the mineral observations. The article contains the wording not anoxic in a sentence describing mixed cultures; no oxygen regime is inferred from that wording. No genome accession is assigned here as a strain-authentication result.
The live taxonomy authority resolves Chroococcidiopsis to genus NCBITaxon:54298. The record preserves the source strain designation in context rather than assigning a species or strain taxon that was not verified.
Original main Figure 4 illustrates the proposed dissolution and particle-attachment sequence. It is not a direct time-resolved causal intervention. Announced supplementary Figures S1-S7 were not acquired through the inspected routes; their humidity, facet-specific, additional diffraction and microscopic details are not treated as verified. The accepted main-paper observations do not establish a universal facet-specific mechanism or quantitative water extraction.

Independent 15-day culture exposure without detected anhydrite formation

other Microbial

Associated Organisms: Chroococcidiopsis (NCBITaxon:54298), Synechocystis sp. PCC 6803 (NCBITaxon:1148)

Douchi2024 tested G-MTQ-3P2 and Synechocystis PCC 6803 on synthetic gypsum and detected no transformation to anhydrite or bassanite after 15 days in the inspected main-paper diffraction experiment. This is an independently reported negative result under its own conditions, not proof of universal impossibility and not a positive microbial mineral-formation mechanism.

Experimental Context & Analytical Limits:
Douchi2024 Results, Figure 1 and Methods, Inoculation and incubation of gypsum chips with flat surfaces and XRD analysis of gypsum phase transition into anhydrite, used rehydrated alpha-plaster gypsum, 15 mm diameter and 2 mm thick, UV-sterilized. Cultures received 100 microliters BG11 per chip in covered sterile six-well plates at 25 degrees C under constant 20 micromol photons/m2/s light. A chamber water layer buffered initial drying; the authors report complete drying after several days. The inoculated treatments were performed in triplicate and compared with chips given 100 microliters sterile BG11. Results specify 3 micrograms chlorophyll per chip, whereas Methods specify 200 micrograms/mL in 100 microliters, equivalent to 20 micrograms per chip; this unresolved loading discrepancy is not silently reconciled. G-MTQ-3P2 came from J. DiRuggiero with an author-reported 16S sequence match. The culture-maintenance pH/carbon-supply description is not imposed as a measured chip-surface pH.
Curated Evidence Points:
Original Figure 1B shows the three replicate diffraction profiles for each cyanobacterial treatment; Figure 1C compares both treatments and the sterile-medium blank with calcium-sulfate reference patterns. The authors report only gypsum after 15 days, without the diagnostic anhydrite/bassanite features. This contradicts an assumption that exposure to these cultures necessarily dehydrates gypsum under the tested conditions. No quantitative detection limit or bound on a very small transformed fraction is given. Figure 2 reports renewed growth of part of the dried Chroococcidiopsis population after transfer to fresh medium, which does not prove structural-water uptake.
This is not an exact replication of the original coupon experiment: synthetic polycrystalline feed, larger surface area, UV rather than autoclave sterilization, initial humidity buffering, light intensity, exposure duration and unresolved biomass loading differ. The paper also describes a 30-day oriented-single-crystal test and scraped-surface diffraction, but those graphics are in unacquired Supplementary Figure S1 and are excluded from the verified comparison. The accepted counterevidence is the fully inspected 15-day main Figure 1. The Methods say diffraction angles are presented for Cu K-alpha while Figure 1B labels a Co wavelength; no numerical peak-position conversion is inferred here.
Current NCBI Taxonomy resolves identifier 1148 to Synechocystis sp. PCC 6803, rank species. This is an authority label, not proof that every PCC 6803 laboratory substrain or stock shares the reported phenotype.
Identifier 54298 is a genus-level mapping. G-MTQ-3P2 remains a source-reported culture designation and is not promoted to an independently verified species or axenic strain.

Sources & References

  1. ima_2026_09: IMA-CNMNC. The New IMA List of Minerals, September 2026. Definitions on PDF page 1, Anhydrite row on page 11 and Gypsum row on page 88; grandfathered mineral identities. Previously acquired official original re-inspected on the access date.
    https://cnmnc.units.it/files/editor/IMA_Master_List_(2026-09).pdf (accessed 2026-10-15)
  2. huang2020: Huang et al. (2020). Mechanism of water extraction from gypsum rock by desert colonizing microorganisms. PNAS 117:10681-10687. Complete original PMC HTML and original Figures 1-4 inspected; announced supplementary PDF not acquired. Read with the published correction and correspondence.
    https://doi.org/10.1073/pnas.2001613117 (accessed 2026-10-15)
  3. huang2020_correction: Correction for Huang et al. (2020), Mechanism of water extraction from gypsum rock by desert colonizing microorganisms. PNAS 117:29989. Corrects gypsum coupon dimensions in two locations to 5 mm by 8 mm by 0.5 mm.
    https://doi.org/10.1073/pnas.2021524117 (accessed 2026-10-15)
  4. wierzchos2020: Wierzchos et al. (2020). Crystalline water in gypsum is unavailable for cyanobacteria in laboratory experiments and in natural desert endolithic habitats. PNAS 117:27786-27787. Complete two-page original from an author institutional site, Figure 1 and Table 1.
    https://doi.org/10.1073/pnas.2013134117 (accessed 2026-10-15)
  5. huang2020_reply: Huang et al. (2020). Reply to Wierzchos et al.: Microorganism-induced gypsum to anhydrite phase transformation. PNAS 117:27788-27790. Complete official PMC HTML and original Figures 1-2; clarification of the same experiment, not independent replication.
    https://doi.org/10.1073/pnas.2018184117 (accessed 2026-10-15)
  6. douchi2024: Douchi et al. (2024; online 2023). Dryland Endolithic Chroococcidiopsis and Temperate Fresh Water Synechocystis Have Distinct Membrane Lipid and Photosynthesis Acclimation Strategies upon Desiccation and Temperature Increase. Plant and Cell Physiology 65:939-957. Complete publisher HTML and original main Figures 1-8 inspected. Accepted mineral comparison is confined to Figure 1 and the corresponding 15-day methods; supplementary Figure S1 was not acquired.
    https://doi.org/10.1093/pcp/pcad139 (accessed 2026-10-15)
  7. murray2021: Murray et al. (2021). Draft Metagenomes of Endolithic Cyanobacteria and Cohabitants from Hyper-Arid Deserts. Microbiology Resource Announcements 10:e00206-21. Complete official JATS, Announcement and Table 1; culture provenance only.
    https://doi.org/10.1128/MRA.00206-21 (accessed 2026-10-15)
  8. ncbi_chroococcidiopsis: NCBI Taxonomy 54298, Chroococcidiopsis, genus. Current taxonomy XML verifies only the genus, not a strain-specific identifier for G-MTQ-3P2.
    https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?id=54298 (accessed 2026-10-15)
  9. ncbi_synechocystis6803: NCBI Taxonomy 1148, Synechocystis sp. PCC 6803; current authority label, rank species. This identifier does not independently authenticate the experimental culture stock.
    https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?id=1148 (accessed 2026-10-15)
  10. handbook_anhydrite: Handbook of Mineralogy. Anhydrite, complete one-page formula, crystallography and natural-occurrence entry, copyright 2001-2005.
    https://www.handbookofmineralogy.org/pdfs/anhydrite.pdf (accessed 2026-10-15)

Curation History

Timestamp Curator Action Summary
2026-10-15T05:11:31Z codex (GPT-6; codex) CREATE Curated anhydrite identity with disputed culture-associated gypsum transformation and independent negative evidence.

Record source: data/records/anhydrite.yaml