Zinkgruvanite, Ba<sub>4</sub>Mn<sup>2+</sup><sub>4</sub>Fe<sup>3+</sup><sub>2</sub>(Si<sub>2</sub>O<sub>7</sub>)<sub>2</sub>(SO<sub>4</sub>)<sub>2</sub>O<sub>2</sub>(OH)<sub>2</sub>, a new ericssonite-group mineral from the Zinkgruvan Zn-Pb-Ag-Cu deposit, Askersund, Örebro County, Sweden
<p><span id="page660"/>Zinkgruvanite, ideally Ba<span class="inline-formula"><sub>4</sub></span>Mn<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M10" display="inline...
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| Formato: | article |
| Lenguaje: | EN |
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Copernicus Publications
2021
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| Acceso en línea: | https://doaj.org/article/101c341065a9441180cc4298a18ca055 |
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| Sumario: | <p><span id="page660"/>Zinkgruvanite, ideally
Ba<span class="inline-formula"><sub>4</sub></span>Mn<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M10" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">4</mn><mrow><mn mathvariant="normal">2</mn><mo>+</mo></mrow></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="12pt" height="16pt" class="svg-formula" dspmath="mathimg" md5hash="28b8815ddf29031da9a15ec20bc0c62d"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="ejm-33-659-2021-ie00005.svg" width="12pt" height="16pt" src="ejm-33-659-2021-ie00005.png"/></svg:svg></span></span>Fe<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M11" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">2</mn><mrow><mn mathvariant="normal">3</mn><mo>+</mo></mrow></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="12pt" height="17pt" class="svg-formula" dspmath="mathimg" md5hash="7ab3e60d293e5f6af16705622d6ca4dd"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="ejm-33-659-2021-ie00006.svg" width="12pt" height="17pt" src="ejm-33-659-2021-ie00006.png"/></svg:svg></span></span>(Si<span class="inline-formula"><sub>2</sub></span>O<span class="inline-formula"><sub>7</sub>)<sub>2</sub></span>(SO<span class="inline-formula"><sub>4</sub>)<sub>2</sub></span>O<span class="inline-formula"><sub>2</sub></span>(OH)<span class="inline-formula"><sub>2</sub></span>,
is a new member of the ericssonite group, found in Ba-rich drill core
samples from a sphalerite- and galena- and diopside-rich metatuffite succession
from the Zinkgruvan mine, Örebro County, Sweden. Zinkgruvanite is
associated with massive baryte, barytocalcite, diopside and minor witherite,
cerchiaraite-Al, and sulfide minerals. It occurs as subhedral to euhedral
flattened and elongated crystals up to 4 mm. It is almost black and semi-opaque
with a dark-brown streak. The lustre is vitreous to sub-adamantine on
crystal faces and resinous on fractures. The mineral is brittle with an uneven
fracture. VHN<span class="inline-formula"><sub>100</sub>=539</span>, and H<span class="inline-formula"><sub>Mohs</sub></span> <span class="inline-formula">≈</span> 4.5.
In thin fragments, it is reddish-black, translucent and optically biaxial
(<span class="inline-formula">+</span>), 2<span class="inline-formula"><i>V</i><sub><i>z</i></sub></span> <span class="inline-formula">></span> 70<span class="inline-formula"><sup>∘</sup></span>. Pleochroism is strong and deep
brown-red (<span class="inline-formula"><strong><em>E</em></strong></span> <span class="inline-formula">⊥</span> <span class="inline-formula"><i>{</i>001<i>}</i></span> cleavage) to
olive-pale-brown. Chemical point analyses by WDS-EPMA (wavelength-dispersive X-ray spectroscopy electron probe microanalyser) together with iron
valencies determined from Mössbauer spectroscopy yielded the empirical
formula (based on 26 O<span class="inline-formula">+</span>OH<span class="inline-formula">+</span>F<span class="inline-formula">+</span>Cl anions):
(Ba<span class="inline-formula"><sub>4.02</sub></span>Na<span class="inline-formula"><sub>0.03</sub>)<sub>Σ4.05</sub></span>(Mn<span class="inline-formula"><sub>1.79</sub></span>Fe<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M33" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">1.56</mn><mrow><mn mathvariant="normal">2</mn><mo>+</mo></mrow></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="18pt" height="17pt" class="svg-formula" dspmath="mathimg" md5hash="4e2657da9bf1a1005c61b46e5a0b16ff"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="ejm-33-659-2021-ie00007.svg" width="18pt" height="17pt" src="ejm-33-659-2021-ie00007.png"/></svg:svg></span></span>Fe<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M34" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">0.42</mn><mrow><mn mathvariant="normal">3</mn><mo>+</mo></mrow></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="18pt" height="17pt" class="svg-formula" dspmath="mathimg" md5hash="95e15facba73379041c2b38787c09e66"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="ejm-33-659-2021-ie00008.svg" width="18pt" height="17pt" src="ejm-33-659-2021-ie00008.png"/></svg:svg></span></span>Mg<span class="inline-formula"><sub>0.14</sub></span>Ca<span class="inline-formula"><sub>0.10</sub></span>Ni<span class="inline-formula"><sub>0.01</sub></span>Zn<span class="inline-formula"><sub>0.01</sub>)<sub>Σ4.03</sub></span>(Fe<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M39" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">1.74</mn><mrow><mn mathvariant="normal">3</mn><mo>+</mo></mrow></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="18pt" height="17pt" class="svg-formula" dspmath="mathimg" md5hash="b794586e145dd404b293762b8d9f995d"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="ejm-33-659-2021-ie00009.svg" width="18pt" height="17pt" src="ejm-33-659-2021-ie00009.png"/></svg:svg></span></span>Ti<span class="inline-formula"><sub>0.20</sub></span>Al<span class="inline-formula"><sub>0.06</sub>)<sub>Σ2.00</sub></span>Si<span class="inline-formula"><sub>4</sub></span>(S<span class="inline-formula"><sub>1.61</sub></span>Si<span class="inline-formula"><sub>0.32</sub></span>P<span class="inline-formula"><sub>0.07</sub>)<sub>Σ1.99</sub></span>O<span class="inline-formula"><sub>24</sub></span>(OH<span class="inline-formula"><sub>1.63</sub></span>Cl<span class="inline-formula"><sub>0.29</sub></span>F<span class="inline-formula"><sub>0.08</sub>)<sub>Σ2.00</sub></span>. The
mineral is triclinic, in space group <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M50" display="inline" overflow="scroll" dspmath="mathml"><mrow><mi>P</mi><mover accent="true"><mn mathvariant="normal">1</mn><mo mathvariant="normal">¯</mo></mover></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="16pt" height="12pt" class="svg-formula" dspmath="mathimg" md5hash="e86b7352d082dc86c64765dda8a595db"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="ejm-33-659-2021-ie00010.svg" width="16pt" height="12pt" src="ejm-33-659-2021-ie00010.png"/></svg:svg></span></span>, with unit-cell parameters <span class="inline-formula"><i>a</i>=5</span>.3982(1) Å, <span class="inline-formula"><i>b</i>=7</span>.0237(1) Å, <span class="inline-formula"><i>c</i>=14</span>.8108(4) Å, <span class="inline-formula"><i>α</i>=</span>
98.256(2)<span class="inline-formula"><sup>∘</sup></span>, <span class="inline-formula"><i>β</i>=</span> 93.379(2)<span class="inline-formula"><sup>∘</sup></span>,
<span class="inline-formula"><i>γ</i>=</span> 89.985(2)<span class="inline-formula"><sup>∘</sup></span> and <span class="inline-formula"><i>V</i>=</span> 554.75(2) Å<span class="inline-formula"><sup>3</sup></span> for <span class="inline-formula"><i>Z</i>=1</span>. The eight strongest X-ray powder diffraction lines are the following (<span class="inline-formula"><i>d</i></span> Å (I %; hkl)): 3.508 (70; 103), 2.980(70; 11<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M64" display="inline" overflow="scroll" dspmath="mathml"><mover accent="true"><mn mathvariant="normal">4</mn><mo mathvariant="normal">‾</mo></mover></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="8pt" height="13pt" class="svg-formula" dspmath="mathimg" md5hash="345c80e7f9ff65e352fcb2076ac3394f"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="ejm-33-659-2021-ie00011.svg" width="8pt" height="13pt" src="ejm-33-659-2021-ie00011.png"/></svg:svg></span></span>), 2.814 (68; 1<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M65" display="inline" overflow="scroll" dspmath="mathml"><mover accent="true"><mn mathvariant="normal">2</mn><mo mathvariant="normal">‾</mo></mover></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="8pt" height="13pt" class="svg-formula" dspmath="mathimg" md5hash="daa485d23ee07de0d10cd0e552135347"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="ejm-33-659-2021-ie00012.svg" width="8pt" height="13pt" src="ejm-33-659-2021-ie00012.png"/></svg:svg></span></span>2),
2.777 (70; 121), 2.699 (714; 200), 2.680 (68; 20<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M66" display="inline" overflow="scroll" dspmath="mathml"><mover accent="true"><mn mathvariant="normal">1</mn><mo mathvariant="normal">‾</mo></mover></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="8pt" height="13pt" class="svg-formula" dspmath="mathimg" md5hash="34b6701d827c435e6b3205503edf756f"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="ejm-33-659-2021-ie00013.svg" width="8pt" height="13pt" src="ejm-33-659-2021-ie00013.png"/></svg:svg></span></span>), 2.125 (100; 124,
204) and 2.107 (96; <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M67" display="inline" overflow="scroll" dspmath="mathml"><mover accent="true"><mn mathvariant="normal">2</mn><mo mathvariant="normal">‾</mo></mover></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="8pt" height="13pt" class="svg-formula" dspmath="mathimg" md5hash="3e6250055890766015bb16c2b6a27591"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="ejm-33-659-2021-ie00014.svg" width="8pt" height="13pt" src="ejm-33-659-2021-ie00014.png"/></svg:svg></span></span>21). The crystal structure (<span class="inline-formula"><i>R</i><sub>1</sub>=0</span>.0379 for
3204 reflections) is an array of TS (titanium silicate) blocks alternating
with intermediate blocks. The TS blocks consist of HOH sheets (H for
heteropolyhedral and O for octahedral) parallel to (001). In the O sheet, the
Mn<span class="inline-formula"><sup>2+</sup></span>-dominant <span class="inline-formula"><i>M</i><sup>O</sup></span>(1,2,3) sites give ideally Mn<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M71" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">4</mn><mrow><mn mathvariant="normal">2</mn><mo>+</mo></mrow></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="12pt" height="16pt" class="svg-formula" dspmath="mathimg" md5hash="75a030282913f27a2fb5ef5f1e752d05"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="ejm-33-659-2021-ie00015.svg" width="12pt" height="16pt" src="ejm-33-659-2021-ie00015.png"/></svg:svg></span></span> pfu (per formula unit). In the
H sheet, the Fe<span class="inline-formula"><sup>3+</sup></span>-dominant <span class="inline-formula"><i>M</i><sup>H</sup></span> sites and <span class="inline-formula"><i>A</i><sup><i>P</i></sup></span>(1) sites give
ideally Fe<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M75" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">2</mn><mrow><mn mathvariant="normal">3</mn><mo>+</mo></mrow></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="12pt" height="17pt" class="svg-formula" dspmath="mathimg" md5hash="bfb3dbd64914dca614119742ca4e8ef0"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="ejm-33-659-2021-ie00016.svg" width="12pt" height="17pt" src="ejm-33-659-2021-ie00016.png"/></svg:svg></span></span>Ba<span class="inline-formula"><sub>2</sub></span> pfu. In the intermediate block, SO<span class="inline-formula"><sub>4</sub></span>
oxyanions and 11 coordinated Ba atoms give ideally <span class="inline-formula">2×</span> SO<span class="inline-formula"><sub>4</sub></span>Ba pfu. Zinkgruvanite is related to ericssonite and ferroericssonite
in having the same topology and type of linkage of layers in the TS block.
Zinkgruvanite is also closely compositionally related to yoshimuraite,
Ba<span class="inline-formula"><sub>4</sub></span>Mn<span class="inline-formula"><sub>4</sub></span>Ti<span class="inline-formula"><sub>2</sub></span>(Si<span class="inline-formula"><sub>2</sub></span>O<span class="inline-formula"><sub>7</sub>)<sub>2</sub></span>(PO<span class="inline-formula"><sub>4</sub>)<sub>2</sub></span>O<span class="inline-formula"><sub>2</sub></span>(OH)<span class="inline-formula"><sub>2</sub></span>,
via the coupled heterovalent substitution 2 Ti<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M88" display="inline" overflow="scroll" dspmath="mathml"><mrow><msup><mi/><mrow><mn mathvariant="normal">4</mn><mo>+</mo></mrow></msup><mo>+</mo></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="20pt" height="13pt" class="svg-formula" dspmath="mathimg" md5hash="3c898475919aa4ea5288daa2b4a2d501"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="ejm-33-659-2021-ie00017.svg" width="20pt" height="13pt" src="ejm-33-659-2021-ie00017.png"/></svg:svg></span></span> 2
(PO<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M89" display="inline" overflow="scroll" dspmath="mathml"><mrow><msub><mi/><mn mathvariant="normal">4</mn></msub><msup><mo>)</mo><mrow><mn mathvariant="normal">3</mn><mo>-</mo></mrow></msup><mo>→</mo></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="36pt" height="16pt" class="svg-formula" dspmath="mathimg" md5hash="32039fe5ea4263661129399d218c92a5"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="ejm-33-659-2021-ie00018.svg" width="36pt" height="16pt" src="ejm-33-659-2021-ie00018.png"/></svg:svg></span></span>2 Fe<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M90" display="inline" overflow="scroll" dspmath="mathml"><mrow><msup><mi/><mrow><mn mathvariant="normal">3</mn><mo>+</mo></mrow></msup><mo>+</mo></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="20pt" height="13pt" class="svg-formula" dspmath="mathimg" md5hash="58c7ba42b8bb75ee58b01bfeee7f4b14"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="ejm-33-659-2021-ie00019.svg" width="20pt" height="13pt" src="ejm-33-659-2021-ie00019.png"/></svg:svg></span></span> 2 (SO<span class="inline-formula"><sub>4</sub>)<sup>2−</sup></span> but presents a
different type of linkage. The new mineral probably formed during a late
stage of regional metamorphism of a Ba-enriched, syngenetic protolith,
involving locally generated oxidized fluids of high salinity.</p> |
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