Aleutite

{{Short description|Mineral}} {{Infobox mineral | name = Aleutite | category = vanadate and arsenate | image = | caption = | formula = [Cu₅O₂](AsO₄)(VO₄) · (Cu_0.5□_0.5)Cl | IMAsymbol = Aeu<ref name=Waar>{{Cite journal|last=Warr|first=L.N.|date=2021|title=IMA–CNMNC approved mineral symbols|journal=Mineralogical Magazine|volume=85|issue=3|pages=291–320|doi=10.1180/mgm.2021.43|bibcode=2021MinM...85..291W|s2cid=235729616|doi-access=free}}</ref> | molweight = 287.26 | strunz = 4/K.01-10 | system = Monoclinic | class = 2/m - Prismatic | symmetry = ''C2/m'' | unit cell = a = 18.090(2)&nbsp;Å, b = 6.2248(6)&nbsp;Å; <br/>c = 8.2465(9)&nbsp;Å; <br/>β= 90.597(2)°;<br/>Z = 4&nbsp; | color = Dark red | habit = | twinning = | cleavage = none observed | fracture = Irregular/Uneven | tenacity = Brittle | mohs = | luster = Adamantine | polish = | refractive = | opticalprop = | birefringence = | dispersion = | pleochroism = | fluorescence= | absorption = | streak = Reddish black | gravity = | density = 4.887 g/cm³ | melt = | fusibility = | diagnostic = | solubility = | diaphaneity = Transparent | other = | references = <ref name=Siidra>Siidra, O. I., Nazarchuk, E. V., Agakhanov, A. A., &amp; Polekhovsky, Y. S. (2019). Aleutite [cu5O2](aso4)(vo4)·(cu0.5□0.5)cl, a new complex salt-inclusion mineral with Cu2+Substructure derived from a kagome-net. Mineralogical Magazine, 83(6), 847–853. https://doi.org/10.1180/mgm.2019.42</ref><ref name=Mindat>Hudson Institute of Mineralogy, 2019, Aleutite: https://www.mindat.org/min-52922.html (accessed December 2023)</ref> }}

'''Aleutite''' is both a vanadate and arsenate mineral but it can also be considered as a natural salt-inclusion phase. It was first discovered at Second scoria cone of the Great Fissure Tolbachik eruption in the summer of 2015 in Kamchatka, Russia. Aleutite is a fumarolic mineral found with many other newly discovered minerals at this location. It gained the name from the Aleuts, the ethnic group who are the original inhabitants living on the Commander Islands, Aleutsky District, Kamchatka Krai. This mineral is very brittle and has a dark red color. Aleutite is a new structure type, the structure was refined as a 2-component twin, the twin ratio equals (0.955:0.045). <ref name=Siidra />

==Occurrence== Aleutite occurs as a product of fumarolic activity. It was found in the summer of 2015 in Yadovitaya fumarole at the Second Scoria Cone of the Northern Breakthrough of the Great Fissure Tolbachik Eruption in Kamchatka, Russia. The Second Scoria Cone is located approximately 18 km SSW of the active shield volcano Ploskiy Tolbachik. The temperature of gases at the sampling location was about 300&nbsp;°C. Aleutite could be deposited directly from the gas phase as a volcanic sublimate. All the recovered samples were immediately packed and isolated to avoid any contact with atmosphere. Aleutite is very rare and closely associates with anhydrite. Other associated minerals are euchlorine, kamchatkite, langbeinite, lyonsite, pseudolyonsite, tenorite, hematite. <ref name=Siidra />

==Physical properties==

Aleutite occurs as individual crystals in the masses of polycrystalline anhydrite. Aleutite is dark red, with reddish black streak, and has an adamantine luster. It is brittle with no visible cleavage observed. Parting was not observed, and its fracture is uneven. The density could not be measured due to lack of sufficient material. The calculated specific gravity is 4.887 g/cm³.<ref name=Siidra />

==Optical properties==

The measured optical properties of Aleutite were found through reflected light. The mineral had high values of refractive indices which is typical of arsenates and vanadates. Reflectance measurements were made using a SiC standard in air which ranged from 400–700 nm. Aleutite is grey with yellowish tint in reflected light, it is non-pleochroic with abundant brown-red internal reflections and a weak bireflectance.<ref name=Siidra />

==Chemical properties== Aleutite is both a vanadate and arsenate that may can compared to averievite which has had a formula of Cu₆(VO₄)₂O₂Cl₂. It may also be comparable with piypite with a formula of K₂Cu₂O(SO₄)₂.<ref name=Mindat /> The empirical formula of Aleutite cab be calculated on the basis of (As+V+Mo+Fe3+) = 2 apfu is Cu_5.40Zn_0.05Ca_0.01As_1.09V_0.84Mo_0.04Fe_0.03K_0.05Pb_0.02Rb_0.01Cs_0.01O_9.97Cl_1.07 or (Cu_4.94Zn_0.05Ca_0.01)_Σ5.00O_2.11[(As_2.11V_0.42Mo_0.02Fe_0.02)_Σ1.00O_Σ3.93]₂ ∙ (Cu_0.46K_0.05Pb_0.02Rb_0.01Cs_0.01)_Σ0.55Cl_1.07. Taking into account structural data, the simplified formula is [Cu₅O₂](AsO₄)(VO₄)·(Cu_0.5□_0.5)Cl. Aleutite is soluble in hot H₂O.<ref name=Siidra />

==Chemical composition== {| class="wikitable" |- ! Constituent !! wt% !! Range |- | MoO₃ || 0.83 || 0.62 – 1.02 |- | As₂O₅ || 18.33 || 17.77 – 19.83 |- | V₂O₅ || 11.13 || 10.56 – 11.85 |- | Fe₂O₃ || 0.36 || 10.56 – 11.85 |- | CuO|| 62.73 || 61.79 – 63.54 |- | ZnO || 0.60 || 0.39 – 0.77 |- | PbO || 0.75 || 0.59 – 0.98 |- | CaO || 0.10 || 0.00 – 0.22 |- | K₂O || 0.35 || 0.24 – 0.47 |- | Cs₂O || 0.16 || 0.05 – 0.31 |- | Rb₂O || 0.18 || 0.09 – 0.27 |- | Cl || 5.54 || 5.40 – 5.78 |- | -Cl=O || 1.25 || |- | Total || 99.81 || 100.02 – 101.83 |}<ref name=Waar /><ref name=Siidra />

==X-ray crystallography== Aleutite is in the monoclinic crystal system and has a space group of C2/m.<ref name=Siidra /> Its unit cell dimensions are as follows: a = 18.0788(9) Å, b = 6.2270(5) Å, c = 8.2445(3) Å, β = 90.56(4)º, V = 928.09(7) ų, Z = 4. Aleutite has a point group of 2/m.<ref name=Mindat /> The [Cu₅O₂]₆₊ band in aleutite can be considered part of a kagome network.

==See also== List of Minerals

==References== {{Reflist}}

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Category:Natural materials Category:Monoclinic minerals Category:Minerals in space group 21 Category:Wikipedia Student Program Category:Arsenate minerals Category:Vanadate minerals Category:Chloride minerals Category:Copper minerals