Andreybulakhite, Ni(C<sub>2</sub>O<sub>4</sub>)  ⋅  2H<sub>2</sub>O, the first natural nickel oxalate
<p>Andreybulakhite, ideally Ni(C<span class="inline-formula"><sub>2</sub></span>O<span class="inline-formula"><sub>4</sub></span>) <span class="inline-formula">⋅</span> 2H<span class="inline-formu...
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| Main Authors: | , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2025-02-01
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| Series: | European Journal of Mineralogy |
| Online Access: | https://ejm.copernicus.org/articles/37/63/2025/ejm-37-63-2025.pdf |
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| Summary: | <p>Andreybulakhite, ideally Ni(C<span class="inline-formula"><sub>2</sub></span>O<span class="inline-formula"><sub>4</sub></span>) <span class="inline-formula">⋅</span> 2H<span class="inline-formula"><sub>2</sub></span>O, is a new member of the humboldtine group, named in honour of Andrey Glebovich Bulakh of Saint Petersburg State University. The mineral was discovered at the Nyud-II (Nud-II) Cu–Ni sulfide deposit, Monchegorsk mafic–ultramafic pluton, Kola Peninsula, Russia. Andreybulakhite forms segregations of platy to prismatic crystals up to <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M13" display="inline" overflow="scroll" dspmath="mathml"><mrow><mn mathvariant="normal">2</mn><mo>×</mo><mn mathvariant="normal">1</mn><mo>×</mo><mn mathvariant="normal">1</mn></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="43pt" height="10pt" class="svg-formula" dspmath="mathimg" md5hash="d929e2aabaa886f370b6ba53bba5c048"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="ejm-37-63-2025-ie00001.svg" width="43pt" height="10pt" src="ejm-37-63-2025-ie00001.png"/></svg:svg></span></span> <span class="inline-formula">µ</span>m in size that are localized in the upper part of the fruiting bodies (apothecia) of <i>Lecanora</i> cf. <i>polytropa</i> lichen, whose colonies overgrow the oxidized surfaces of pyrrhotite–pentlandite–chalcopyrite ore. The mineral is monoclinic, with space group <span class="inline-formula"><i>C</i></span>2/<span class="inline-formula"><i>c</i></span>, <span class="inline-formula"><i>a</i>=11.8392(5)</span> Å, <span class="inline-formula"><i>b</i>=5.3312(2)</span> Å, <span class="inline-formula"><i>c</i>=9.8357(7)</span> Å, <span class="inline-formula"><i>β</i>=126.723(5)</span>°, <span class="inline-formula"><i>V</i>=497.59(3)</span> Å<span class="inline-formula"><sup>3</sup></span> and <span class="inline-formula"><i>Z</i>=4</span>. The Raman spectrum of andreybulakhite contains the following bands (cm<span class="inline-formula"><sup>−1</sup></span>): 1701 (C<span class="inline-formula">=</span>O stretching vibrations and/or multiphonon processes); 1621 (H<span class="inline-formula"><sub>2</sub></span>O bending vibrations); 1454 and 924 (C–O and C–C stretching modes); 597 (Ni–O stretching, C–C–O and O–C–O bending vibrations); and 550, 307 and 226 (predominantly Ni–O stretching and deformation modes). The absorption bands of the infrared spectrum are (cm<span class="inline-formula"><sup>−1</sup></span>) 3389 (O–H stretching vibrations), 1640 (H<span class="inline-formula"><sub>2</sub></span>O bending vibrations), 1357 and 1315 (C–O stretching, C–C stretching), and 818 (Ni–O stretching, C–O and C–C stretching, C–C–O and O–C–O bending vibrations). The empirical formula calculated on the basis of (Ni <span class="inline-formula">+</span> Cu <span class="inline-formula">+</span> Mg <span class="inline-formula">+</span> Co) <span class="inline-formula">=1</span> atom per formula unit is (Ni<span class="inline-formula"><sub>0.63</sub></span>Cu<span class="inline-formula"><sub>0.27</sub></span>Mg<span class="inline-formula"><sub>0.08</sub></span>Co<span class="inline-formula"><sub>0.02</sub>)<sub>Σ1.00</sub></span>(C<span class="inline-formula"><sub>2</sub></span>O<span class="inline-formula"><sub>4</sub></span>) <span class="inline-formula">⋅</span> 2H<span class="inline-formula"><sub>2</sub></span>O. The absence of iron in the mineral is a result of oxidative <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M41" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><msup><mi mathvariant="normal">Ni</mi><mrow><mn mathvariant="normal">2</mn><mo>+</mo></mrow></msup><mo>/</mo><msup><mi mathvariant="normal">Fe</mi><mrow><mn mathvariant="normal">3</mn><mo>+</mo></mrow></msup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="52pt" height="15pt" class="svg-formula" dspmath="mathimg" md5hash="9efcbcd76274bb6c3a635d566edf6dce"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="ejm-37-63-2025-ie00002.svg" width="52pt" height="15pt" src="ejm-37-63-2025-ie00002.png"/></svg:svg></span></span> fractionation during the secondary aqueous alteration of Ni- and Cu-rich sulfides. Andreybulakhite has synthetic Ni and Co counterparts; the latter implies the possibility of formation of its Co analogue in a related cobalt-rich environment.</p> |
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| ISSN: | 0935-1221 1617-4011 |