Orthoclase mineral
Orthoclase is a monoclinic potassium feldspar mineral with ideal formula KAlSi3O8, distinct from microcline, the broader potassium-feldspar family, traded feldspar and potash. The September 2026 IMA list marks it approved by a 1962 special procedure; this is not a numbered approval accession. The curated experiment concerns a source-identified natural sodium-bearing orthoclase crystal, not an ideal chemically pure endmember. Only abiotic hydrothermal dissolution is accepted here; mineral composition does not establish criticality or microbial activity.
Microbial & Biochemical Mechanisms (1)
Abiotic dissolution and etch-pit development on an orthoclase cleavage surface
other
A polished (001) surface developed diamond-shaped etch pits while its exposed surface retreated during alkaline hydrothermal reaction. AFM tracked pit morphology and VSI measured retreat relative to a masked reference. Numerical extrapolations about long-term surface area, pit-wall reactivity and defect effects are model results, not directly measured extraction yields.
Experimental Context & Analytical Limits:
Chapter XII studied a natural Afghanistan orthoclase crystal with no minor phases detected by XRD or SEM. The final journal specifies Rietveld identification and composition K0.75Na0.22Fe0.01Al0.98Si3.02O8. A partly masked sample in a titanium mixed-flow reactor reacted at 180 degrees C and 50 bar for up to 4.8 days in NaOH/AlCl3 solution, with in-situ pH 9.0 ± 0.1 and inlet Al 3.8 ± 0.2 ppm. The run was interrupted at 0.75, 1.56, 2.21 and 4.80 days for surface measurements. These are repeated observations of one run; approximately fifty pits per time point are not fifty independent reactor experiments.
Chapter XII studied a natural Afghanistan orthoclase crystal with no minor phases detected by XRD or SEM. The final journal specifies Rietveld identification and composition K0.75Na0.22Fe0.01Al0.98Si3.02O8. A partly masked sample in a titanium mixed-flow reactor reacted at 180 degrees C and 50 bar for up to 4.8 days in NaOH/AlCl3 solution, with in-situ pH 9.0 ± 0.1 and inlet Al 3.8 ± 0.2 ppm. The run was interrupted at 0.75, 1.56, 2.21 and 4.80 days for surface measurements. These are repeated observations of one run; approximately fifty pits per time point are not fifty independent reactor experiments.
Curated Evidence Points:
Support
Source:
pollet_thesis2016
Chapter XII Methods pp.189–194, Tables XII.1–2 and Figures XII.1–5 directly document the specimen, apparatus, chemistry, diamond pit morphology and increasing surface retreat. Pit depth and wall angle tend to stabilize while lateral extent grows. A non-wetted masked area supplies the surface-height reference; this is an abiotic experiment without an organism or a biotic comparison.
Partial
Source:
pollet_thesis2016
Chapter XII pp.198–209, Figures XII.5–12 and Table XII.3 separate observed topography from a fitted elementary-cell model. Initial surface rounding required an empirical correction, and polishing may have introduced defects. Long-term stabilization and more reactive pit walls are model-dependent interpretations limited to the studied face and conditions. Modelled surface-area changes are not measured mass recovery or independent validation of a universal feldspar mechanism.
Context_only
Source:
pollet_journal2016
Final article Methods 2.1–2.4 corroborate XRD/Rietveld specimen assignment, composition, conditions and repeated-time sampling. The thesis chapter states its article was to be submitted in July 2016 and is the same study, not independent replication. The chapter's original tables and figures support the accepted bounded observations; complete final-journal image equivalence and any unacquired supplemental materials are not asserted. No microbial potassium release, purified product or industrial deployment is established.
Sources & References
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ima_2026_09: IMA-CNMNC. The New IMA List of Minerals, September 2026; definitions pp.1–2 and Orthoclase row PDF p.160, K(AlSi3O8), A, 1962 s.p. Previously acquired official original re-inspected 14 October 2026.
https://cnmnc.units.it/files/editor/IMA_Master_List_(2026-09).pdf (accessed 2026-10-14) -
orthoclase_handbook: Handbook of Mineralogy: Orthoclase, 2001 version 1.2, complete one-page entry; monoclinic KAlSi3O8, alkali-feldspar identity and distinction from microcline.
https://www.handbookofmineralogy.org/pdfs/orthoclase.pdf (accessed 2026-10-14) -
pollet_thesis2016: Pollet-Villard, M. (2016). Évolution de la surface réactive du feldspath potassique au cours de son altération en contexte géothermal : étude expérimentale et modélisation. Université de Strasbourg doctoral thesis, defended 28 September 2016; complete 274-page file acquired, relevant Chapter XII printed pp.185–209 (PDF pp.199–223), Figures XII.1–12 and Tables XII.1–3 inspected.
https://publication-theses.unistra.fr/public/theses_doctorat/2016/Pollet-Villard_Marion_2016_ED413.pdf (accessed 2026-10-14) -
pollet_journal2016: Pollet-Villard, M.; Daval, D.; Fritz, B.; Knauss, K.G.; Schäfer, G.; Ackerer, P. (2016). Influence of etch pit development on the surface area and dissolution kinetics of the orthoclase (001) surface. Chemical Geology 447:79–92. DOI 10.1016/j.chemgeo.2016.09.038. Same-study final journal text checked via the UC repository; final-journal image/download access was incomplete, so direct graphical assessment uses the thesis chapter.
https://doi.org/10.1016/j.chemgeo.2016.09.038 (accessed 2026-10-14)
Curation History
| Timestamp | Curator | Action | Summary |
|---|---|---|---|
2026-10-14T13:14:52.869476+00:00 |
codex (GPT-6; codex) | CREATE | Created orthoclase with dated mineral identity and directly inspected primary thesis evidence for abiotic face-specific dissolution, retaining final-journal access limits and model/measurement boundaries. |
Record source: data/records/orthoclase.yaml