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Zvěstovite-(Zn), Ag6(Ag4Zn2)As4S13, a new tetrahedrite-group mineral from Zvěstov, Czech Republic
Mineralogical Magazine ( IF 2.8 ) Pub Date : 2021-07-05 , DOI: 10.1180/mgm.2021.57
Jiří Sejkora 1 , Cristian Biagioni 2 , Luboš Vrtiška 3 , Yves Moëlo 4
Affiliation  

The new mineral, zvěstovite-(Zn), ideally Ag6(Ag4Zn2)As4S13, was found in quartz–baryte gangue at the mine dump of the abandoned small deposit of Zvěstov, central Bohemia, Czech Republic. Zvěstovite-(Zn) is associated with tennantite-(Zn), tetrahedrite-(Zn), argentotennantite-(Zn), acanthite and supergene azurite and malachite. The new mineral occurs as rare relic anhedral grains rimmed by acanthite, up to 100 μm in size. Zvěstovite-(Zn) is grey, Mohs hardness is ca. 3½–4, in agreement with other members of the tetrahedrite group; the calculated density is 5.16 g.cm–3. In reflected light, zvěstovite-(Zn) is grey with a greenish tint, without bireflectance, pleochroism or anisotropy. Deep red internal reflections are ubiquitous. Reflectance values of zvěstovite-(Zn) in air (R%) are: 28.5 at 470 nm, 26.9 at 546 nm, 25.5 at 589 nm and 23.8 at 650 nm. The empirical formula for zvěstovite-(Zn), based on electron-microprobe analyses (n = 4), is Ag6.27[(Ag3.90Cu0.38)Σ4.28(Zn1.60Fe0.09Cd0.03)Σ1.72]Σ6.00(As2.26Sb1.48)Σ3.74S12.50. The ideal formula is Ag6(Ag4Zn2)As4S13, which requires (in wt.%) Ag 56.01, Zn 6.79, As 15.56 and S 21.64, total 100.00. Zvěstovite-(Zn) is cubic, I$\bar{4}$3m, with unit-cell parameters: a = 10.850(2) Å, V = 1277.3(8) Å3 and Z = 2. The strongest reflections of the calculated powder X-ray diffraction pattern [d, Å (I) (hkl)] are: 3.1321(100) (222), 2.7125(21) (400), 1.9809(11) (521), 1.9180(31) (440) and 1.6357(15) (622). According to the single-crystal X-ray diffraction data (Robs = 0.051), the crystal structure of zvěstovite-(Zn) agrees with the general features of the members of the tetrahedrite group. Zvěstovite-(Zn) is named after its type locality, Zvěstov; the suffix indicates the dominant divalent C-constituent, according to the approved nomenclature of the tetrahedrite group. It is the As-isotype of rozhdestvenskayaite-(Zn). The mineral and its name have been approved by the Commission on New Minerals, Nomenclature and Classification of the International Mineralogical Association (IMA2020-061).



中文翻译:

Zvěstovite-(Zn), Ag6(Ag4Zn2)As4S13,一种来自捷克共和国 Zvěstov 的新四面体矿物群矿物

新矿物 zvěstovite-(Zn),理想情况下是 Ag 6 (Ag 4 Zn 2 )As 4 S 13,是在捷克共和国波希米亚中部 Zvěstov 废弃小型矿床的石英-重晶石脉石中发现的。Zvěstovite-(Zn) 与tennantite-(Zn)、tetrahedrite-(Zn)、argentotennantite-(Zn)、棘长石和表生蓝铜矿和孔雀石有关。这种新矿物以罕见的遗物正面体颗粒的形式出现,周围有棘长石,尺寸可达 100 微米。Zvěstovite-(Zn)为灰色,莫氏硬度为CA。3½–4,与四面体群的其他成员一致;计算出的密度为 5.16 g.cm –3. 在反射光中,zvěstovite-(Zn) 呈带绿色调的灰色,没有双反射、多向色性或各向异性。深红色的内部反射无处不在。zvěstovite-(Zn) 在空气中的反射值 ( R %) 为:470 nm 处28.5、546 nm 处 26.9、589 nm 处 25.5 和 650 nm 处 23.8。zvěstovite-(Zn) 的经验公式基于电子探针分析 ( n = 4),为 Ag 6.27 [(Ag 3.90 Cu 0.38 ) Σ4.28 (Zn 1.60 Fe 0.09 Cd 0.03 ) Σ1.72 ] Σ6.00 (如2.26 Sb 1.48 ) Σ3.74 S 12.50. 理想的配方是Ag 6 (Ag 4 Zn 2 )As 4 S 13,这需要(重量百分比)Ag 56.01、Zn 6.79、As 15.56 和S 21.64,总计100.00。Zvěstovite-(Zn) 是立方体,I $\bar{4}$ 3 m,具有晶胞参数:a = 10.850(2) Å,V = 1277.3(8) Å 3Z = 2。计算的粉末 X 射线衍射图 [ d , Å (I) ( hkl )] 为: 3.1321(100) (222), 2.7125(21) (400), 1.9809(11) (521), 1.9180(31) ( 440) 和 1.6357(15) (622)。根据单晶X射线衍射数据(R obs = 0.051),zvěstovite-(Zn) 的晶体结构与四面体群成员的一般特征一致。Zvěstovite-(Zn)以其类型产地Zvěstov命名;根据批准的四面体群命名法,后缀表示主要的二价 C 成分。它是 rozhdestvenskayaite-(Zn) 的 As 同种型。该矿物及其名称已获得国际矿物学协会新矿物、命名和分类委员会 (IMA2020-061) 的批准。

更新日期:2021-07-05
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