Abstract
A new biogenic, struvite-related phosphate, the ammonium analog of hazenite (AAH), ideally (NH4) NaMg2(PO4)2·14H2O, has been found in cultures containing the bacterial strain Virgibacillus sp.NOT1 (GenBank Accession Number: JX417495.1) isolated from an XVII Century document made of parchment. The chemical composition of AAH, determined from the combination of electron microprobe and X-ray structural analyses, is [(NH4)0.78K0.22]NaMg2(PO4)2·14H2O. Single-crystal X-ray diffraction shows that AAH is orthorhombic with space group Pmnb and unit-cell parameters a = 6.9661(6), b = 25.236(3), c = 11.292(1) Å, and V = 1985.0(3) Å3. Compared with hazenite, the substitution of NH4+for K+results in a noticeable increase of the average A-O (A = NH4++K+) bond length and the unit-cell volume for AAH, as also observed for struvite vs. struvite-K. Both infrared and Raman spectra of AAH resemble those of hazenite, as well as struvite. Our study reveals that AAH forms only in cultures with Na-bearing solutions and pH below 10.0. No AAH or hazenite was found in experiments with the K-bearing solutions, suggesting the necessity of a Na-bearing solution for AAH formation.
Original language | English (US) |
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Pages (from-to) | 1761-1766 |
Number of pages | 6 |
Journal | American Mineralogist |
Volume | 99 |
Issue number | 8-9 |
DOIs | |
State | Published - Aug 1 2014 |
Keywords
- Ammonium phosphate
- X-ray diffraction
- biomineral
- crystal structure
- hazenite
- infrared and Raman spectra
- struvite-type materials
ASJC Scopus subject areas
- Geophysics
- Geochemistry and Petrology