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Crandallite mineral

Crandallite is the calcium aluminium phosphate mineral CaAl3(PO4)(PO3OH)(OH)6, distinct from strontium-dominant goyazite, the broader crandallite group and mixed phosphorite resources. Primary evidence supports laboratory abiotic synthesis and partial thermal dehydroxylation of crandallite-bearing preparations. Natural crandallite was also identified in mixed Croatian phosphorite, but the associated microbial observations do not establish a crandallite-specific extraction or formation mechanism. No mineral criticality, industrial recovery, fertilizer performance or microbial recovery yield is asserted.

Microbial & Biochemical Mechanisms (1)

Abiotic synthesis and partial thermal dehydroxylation of crandallite-bearing solids

other

Hydrothermal reagent treatment produced crandallite-bearing preparations; subsequent heating removed structural water and reduced crystallinity. This is laboratory solid transformation, not microbial extraction or recovery from waste.

Experimental Context & Analytical Limits:
Gilkes1983 Materials and methods (page 221, PDF page 1) crystallized gels made from sodium aluminate, calcium chloride and phosphoric acid, substituting strontium chloride for calcium chloride across the series. Gels were held for two weeks at 200 degrees C and 1.5 million N/m2 in a stainless-steel pressure vessel with a glass insert. Powder XRD used a quartz internal standard. TGA and differentiated TGA used 10 mg samples in flowing air at 10 degrees C/min; DTA used 100 mg under the same stated heating conditions. Exact starting reagent amounts, independent synthesis replicates and an isolated-product yield are not reported in this article. This is the same experimental series curated in the companion mineral record, not independent replication. The separate crandallite calcination arm (page 226, PDF page 6) heated subsamples for six hours in a muffle furnace at temperatures between 250 and 600 degrees C before XRD. It must not be substituted for the continuously heated thermal-analysis arm.
Curated Evidence Points:
Context_only Source: ima_2026_09
The exact Crandallite row gives CaAl3(PO4)(PO3OH)(OH)6 and status Rd, 1999 s.p.; page 1 defines Rd as redefined. This is mineral identity, not a critical-material designation or certification of experimental purity.
The complete entry independently supports the ideal calcium endmember and natural substituted compositions. The shared group name does not make every aluminium phosphate crandallite.
Pages 221-225, Table II and Figures 1-4 support formation of the assigned synthetic phase. The nominal calcium endmember has reported a=7.007 and c=16.216 angstrom; SEM and selected-area electron diffraction characterize larger tapered crystals as well as aggregates of plates. Morphology alone is not the phase identification.
Pages 221-223, Figure 1 and Table II identify crandallite-goyazite as the major series phases but explicitly report minor boehmite and strontium-substituted hydroxylapatites. The composition axis is mole percent Sr in the original gel, not a measured phase-specific Sr occupancy. Unit-cell estimates use only the well-resolved 303 and 220 reflections because other assignments are uncertain. Neither a pure endmember recovery yield nor a quantitative phase fraction follows from these measurements.
Thermal analysis on pages 226-227 and Figure 7 reports that after six-hour calcination about 80% had dehydroxylated at 450 degrees C to an amorphous residue, while about 6% crandallite persisted at temperatures up to 500 degrees C. These are the authors' approximate solid-transformation statements without reported uncertainty or a closed phase mass balance, not phosphorus extraction percentages. Residual diffraction shows contraction along c and expansion along a with heating.
Pages 225-226 and Figures 5-6 distinguish DTA from DTGA peak temperatures; DTA peaks are systematically higher, possibly because its larger sample slows water escape. The highest-temperature feature is assigned to boehmite impurity, not the phosphate mineral. Differences in crystal size also confound a composition-only explanation. Table I compiles earlier literature, including substituted or mixed natural specimens; those entries are not new experiments or universal decomposition thresholds.
Context_only Source: bermanec2012
Sections 2.1-3.1, Figure 2, Table 1, Figure 5 and Figure 6B (pages 68-72, PDF pages 2-6) identify crandallite in Ervenik_pink and Ervenik_mix phosphorite from old mine dumps by powder diffraction, local Ca-Al-P composition and microscopy. Crandallite occurs with apatite and bauxitic material; neither a pure crandallite feed nor a measured phase fraction was prepared. The proposed early-diagenetic sequence in Section 4 is an interpretation, not an inoculated formation experiment.
Context_only Source: bermanec2012
Sections 2.2 and 3.2, Table 2 (pages 68-72, PDF pages 2-6) incubated 1 g fractions with 9 mL 0.05 mol/L NaCl for four days at 22 degrees C in darkness, 70 rpm and no additional aeration. Native viable saprophyte counts increased in white and mixed fractions but not significantly in the pink fraction. The proposed inhibitory role of crandallite aluminium was not isolated using matched pure-mineral or aluminium controls; it remains a hypothesis.
Context_only Source: bermanec2012
The separate experiment with author-reported Acinetobacter junii DSM 1532 used autoclaved material, 24 hours at 30 degrees C and 70 rpm. Figures 7-8 and the ICP-MS paragraph/Table 3 specifically concern Ervenik_white, assigned predominantly fluorapatite in Figure 2 and Table 1. These results cannot establish crandallite dissolution, even though later text attributes release to hydroxylapatite. Table 3 calls its blank an absence-of-bacteria arm, whereas the prose identifies a blank NaCl solution without clearly specifying a matched mineral-bearing sterile control. No crandallite-specific metal-release or microbial-causality claim is adopted.
Context_only Source: ncbi_junii
The current species-level taxonomy supports the name Acinetobacter junii used in the excluded mixed-feed biological context. It is not verification of DSM 1532, and no organism is attached to the abiotic crandallite mechanism.

Sources & References

  1. ima_2026_09: IMA-CNMNC. The New IMA List of Minerals, September 2026; definitions PDF page 1, Crandallite page 50 and Goyazite page 85, both redefined (Rd), 1999 special procedure.
    https://cnmnc.units.it/files/editor/IMA_Master_List_(2026-09).pdf (accessed 2026-10-15)
  2. handbook_crandallite: Handbook of Mineralogy, Crandallite, complete one-page identity entry; ideal formula, diffraction, composition and natural occurrence.
    https://handbookofmineralogy.org/pdfs/crandallite.pdf (accessed 2026-10-15)
  3. gilkes1983: Gilkes and Palmer (1983). Synthesis, properties, and dehydroxylation of members of the crandallite-goyazite series. Mineralogical Magazine 47:221-227. Complete seven-page original, Tables I-II and Figures 1-7; acquired from RRUFF current .net archive.
    https://doi.org/10.1180/minmag.1983.047.343.13 (accessed 2026-10-15)
  4. bermanec2012: Bermanec et al. (2012). Mineralogical and geomicrobiological investigation of phosphorite from Ervenik, Croatia. Geologia Croatica 65(1):67-75. Complete publisher PDF, nine article pages plus blank page 76; Figures 1-8 and Tables 1-3.
    https://doi.org/10.4154/GC.2012.05 (accessed 2026-10-15)
  5. ncbi_junii: NCBI Taxonomy 40215, Acinetobacter junii, species-level identity checked on 15 October 2026; does not independently authenticate the paper-reported DSM 1532 stock.
    https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?id=40215 (accessed 2026-10-15)

Curation History

Timestamp Curator Action Summary
2026-10-15T07:20:51.407876Z codex (GPT-6; codex) CREATE Added a distinct mineral with complete primary-supported abiotic transformation, verified identity, explicit phase impurities and experimental scope; no inherited criticality or microbial recovery claim.

Record source: data/records/crandallite.yaml