Microcline mineral
Microcline is a triclinic potassium feldspar mineral with ideal formula KAlSi3O8, distinct from orthoclase, the potassium-feldspar family and traded feldspar. The September 2026 IMA list records grandfathered status. Curated field specimens differ in accessory minerals: the South Dakota material contains albite intergrowths with apatite inclusions, whereas the Ontario comparison was homogeneous and phosphorus-poor. Their behavior is not a chemically pure microcline endmember response. No criticality designation is inherited from feldspar commodity or constituent elements.
Microbial & Biochemical Mechanisms (1)
Nutrient-associated colonization and weathering of heterogeneous microcline specimens
bioleaching
Microbial
Indigenous groundwater microorganisms colonized and were associated with surface alteration of the phosphorus-bearing South Dakota microcline specimen in field microcosms. The phosphorus-poor Ontario specimen showed sparse attached cells and no visible chemical weathering. These specimen-dependent observations support microbial weathering as an interpretation, but neither quantify phase-specific dissolution nor demonstrate potassium or phosphorus recovery. Organic-acid or ligand attack is proposed, not causally isolated.
Experimental Context & Analytical Limits:
Rogers1998 exposed source-characterized natural specimens in punctured 8 mL bottles within background and petroleum-contaminated groundwater wells at Bemidji, Minnesota. Crushed 5–10 mm chips were ultrasonically cleaned four times for 15 seconds and dry-sterilized for approximately two hours at 150 degrees C. Methods describe 3–12 month exposures; the microcline image in Figure 6 is after approximately one year. Field water chemistry was measured rather than held at a laboratory setpoint. Mineral characterization included optical microscopy, SEM-EDS, XRD, electron microprobe and whole-rock analysis. Apatite in the South Dakota specimen is hosted within intergrown albite, not demonstrated as phosphorus substitution in the microcline lattice. Attached organisms were described morphologically; no strain-resolved causal agent or taxon identifier is asserted.
Rogers1998 exposed source-characterized natural specimens in punctured 8 mL bottles within background and petroleum-contaminated groundwater wells at Bemidji, Minnesota. Crushed 5–10 mm chips were ultrasonically cleaned four times for 15 seconds and dry-sterilized for approximately two hours at 150 degrees C. Methods describe 3–12 month exposures; the microcline image in Figure 6 is after approximately one year. Field water chemistry was measured rather than held at a laboratory setpoint. Mineral characterization included optical microscopy, SEM-EDS, XRD, electron microprobe and whole-rock analysis. Apatite in the South Dakota specimen is hosted within intergrown albite, not demonstrated as phosphorus substitution in the microcline lattice. Attached organisms were described morphologically; no strain-resolved causal agent or taxon identifier is asserted.
Curated Evidence Points:
Support
Source:
rogers_1998
Methods pp.1533–1534 and Results pp.1535–1538, Tables 1–2 and Figures 1, 3 and 6 document the contrasting specimen composition, attached cells and altered South Dakota surfaces versus nearly barren, unaltered Ontario material. Enrichment cultures from all tested specimens were positive for fermenters, iron reducers and methanogens, including sparsely colonized specimens; sparse visible attachment is not evidence of sterile material or a taxon-specific mechanism.
Partial
Source:
rogers_1998
Figure 7 compares separate abiotic acid-weathering experiments with the field surfaces, but laboratory pH 3/5 acid conditions are not a matched sterile field control. Accessory apatite/albite, field chemistry and surface heterogeneity prevent assignment of nutrient release exclusively to microcline. Replicated phase-specific dissolution or recovery mass balances are absent from the accepted claim. The abstract and Table 1/2004 Table 1 differ in microcline versus anorthoclase phosphorus values; no exact phosphorus grade is adopted.
Partial
Source:
rogers_2004
Section 3.1 p.98 explicitly summarizes the earlier feldspar field lineage, describing microcline as less colonized and lightly etched, whereas Rogers1998 Figure 6 describes extensive weathering. These qualitative descriptions are retained without a universal extent claim or counting the 2004 summary as independent field replication. The new 2004 field-chip experiment concerned manufactured glasses, not a new microcline field trial.
Partial
Source:
rogers_2004
The distinct laboratory arm (Methods 2.5, Results 3.3, Figures 6–10 and Table 5) limits generalization: microcline-supported biomass increased but there was no corresponding silicon increase, and Table 5 marks microcline weathering absent. Four 40 mL microcosms per material used 4 g sterile chips, 50:50 anaerobic groundwater/deionized water, a native sediment inoculum, added 1 mM 3,4-dihydroxybenzoic acid and three months at 25 degrees C in darkness. Added air precipitated groundwater iron, and inoculum Tween 80 contributed some phosphorus. The model ligand was supplied, not shown to be secreted at that concentration. Silicon/phosphate plots subtract sterile controls; iron subtracts the bottle blank. Cell counts include viable and nonviable cells. These outcomes do not establish microbial necessity for phosphorus release, and an increase in biomass is not proof of increased microcline dissolution.
Context_only
Source:
rogers_2004
Separate abiotic powder reactors at pH 5 compared acetate with the model ligand. Their dissolution results must not be treated as live-microbial performance. Neither the field association nor laboratory assays establish isolated product recovery or industrial mineral extraction.
Sources & References
-
ima_2026_09: IMA-CNMNC. The New IMA List of Minerals, September 2026; definitions pp.1–2 and Microcline row PDF p.144, K(AlSi3O8), grandfathered (G), original description 1830. Retained official original re-inspected 14 October 2026.
https://cnmnc.units.it/files/editor/IMA_Master_List_(2026-09).pdf (accessed 2026-10-14) -
microcline_handbook: Handbook of Mineralogy: Microcline, 2001 version 1.2; complete one-page entry, triclinic KAlSi3O8 and perthitic albite intergrowths.
https://www.handbookofmineralogy.org/pdfs/microcline.pdf (accessed 2026-10-14) -
rogers_1998: Rogers, J.R.; Bennett, P.C.; Choi, W.J. (1998). Feldspars as a source of nutrients for microorganisms. American Mineralogist 83:1532–1540. DOI 10.2138/am-1998-11-1241. Complete nine-page original, Tables 1–2 and Figures 1–7 inspected.
https://doi.org/10.2138/am-1998-11-1241 (accessed 2026-10-14) -
rogers_2004: Rogers, J.R.; Bennett, P.C. (2004). Mineral stimulation of subsurface microorganisms: release of limiting nutrients from silicates. Chemical Geology 203:91–108. DOI 10.1016/j.chemgeo.2003.09.001. Complete eighteen-page original, Tables 1–5 and Figures 1–10 inspected; field feldspar observations summarize the earlier study, whereas laboratory microcosms are a distinct assay.
https://doi.org/10.1016/j.chemgeo.2003.09.001 (accessed 2026-10-14)
Curation History
| Timestamp | Curator | Action | Summary |
|---|---|---|---|
2026-10-14T13:58:39.560579+00:00 |
codex (GPT-6; codex) | CREATE | Created distinct microcline record from complete primary field and laboratory evidence, retaining accessory-phase provenance, Ontario null, shared field lineage and absent laboratory silicon enhancement. |
Record source: data/records/microcline.yaml