Langit z Mytinky u Horni Halze v Krusnych horach (Ceska republika)

Horní Halže – Mýtinka is a mineral occurrence located near Mýtinka in the Krušné hory Mts. In the past, the area was intensively mined for iron (namely hematite in quartz veins). Quartz veins are located on complicated intersections of fault systems in mica schists and migmatites (Urban – Crkal 2021). Recently, Sejkora et al. (2021) described rich Cu mineralization found in the remains of old mine dumps. Sulfide mineralization is represented by pyrite, djurleite, roxbyite, anilite, spionkopite, bornite and covellite, supergene phases by malachite, brochantite, liebethenite and pseudomalachite.

The studied material (thin blue coating on a part of a single sulfide grain 3 mm in size; Fig. 1) was found by the first author in 2021 at the old mine dump and matches the material described by Sejkora et al. (2021). The blue phase was identified as langite [Cu4(SO4)(OH)6 · 2H2O] using combination of EDS, Raman and pXRD. Chemical composition of examined mineral coating was analyzed using EDS, which detected presence of Cu, S and O contents only (with Cu significantly higher than S). Raman spectrum of langite from Mýtinka (Fig. 2, Tab. 1) was acquired using a HORIBA LabRam spectrometer and the data were processed using Systat PeakFit software. Proposed spectrum model is in very good agreement with empirical data (r2 = 0.992). Assignment of individual bands according to Martens et al. (2002, 2003) is proposed in Table 1. Raman spectrum of langite is similar to those of posnjakite [Cu4(SO4)(OH)6 · H2O] and wroewolfeite [Cu4(SO4)(OH)6 · H2O]. By combining (poorly and only partially presented) data of Frost et al. (2004) and Martens et al. (2002), following differences among these phases were identified. Bands at 155 and 258 (262 in this work) cm–1 are present in the Raman spectrum of langite but missing in that of posnjakite. The Raman spectrum of wroewolfeite is devoid of bands at 507 and 596 (500 and 598 in this work) cm–1, characteristic of langite, and at 511 and 596 cm–1, characteristic of posnjakite.

About 15 fragments of the coating, 20–100 µm in size, were analyzed on Panalytical X’Pert powder XRD diffractometer. Only four diffraction maxima were obtained due to a very small amount of material available. Nevertheless, corresponding d-values are in a good agreement with data for langite (Tab. 2; Galy et al. 1984).

References

Bloise, A. – Dattola. L. – De Luca, R. – Miriello, D. (2023): Anglesite, Cerussite, Gypsum, Langite, Malachite, and Posnjakite: New Occurrences in the Calabria Region (Southern Italy). – Appl. Sci. 13, 2200.View article

Frost, L. R. – Williams, P. A. – Martens, W. – Leverett, P. – Kloprogge, J. T. (2004): Raman spectroscopy of basic copper(II) and some complex copper(II) sulfate minerals: Implications for hydrogen bonding. – Am. Min. 89, 1130–1137.View article

Galy, J. – Jaud, J. – Pulou, R. – Sempere, R. (1984): Structure cristalline de la langite, Cu4[SO4(OH)6H2O]·H2O. – Bull. Minéral. 107, 641–648.

Gražulis, S. – Daškevič, A. – Merkys, A. – Chateigner, D. – Lutterotti, L. – Quirós, M. – Serebryanaya, N. R. – Moeck, P. – Downs, R. T. – LeBail, A. (2012): Crystallography Open Database (COD): an open-access collection of crystal structures and platform for world-wide collaboration. – Nucleic Acids Res. 40, D420–D427.View article

Hawthorne, F. C. – Groat, L. A. (1985): The crystal structure of wroewolfeite, a mineral with [Cu4(OH)6(SO4)(H2O)] sheets. – Am. Min. 70, 1050–1055.

Martens, W. – Frost, R. L. – Klopproge, J. T. – Williams, P. A. (2003): Raman spectroscopic study of the basic copper sulphates – implications for copper corrosion and ‘bronze disease’. – J. Raman Spectrosc. 34, 145–151.View article

Mellini, M. – Merlino, S. (1979): Posnjakite: [Cu4(OH)6(H2O)O] octahedral sheets in its structure. – Z. Kristallogr. 149, 249–257.

Plášil, J. – Buixaderas, E. – Čejka, J. – Sejkora, J. – Jehlička, J. – Novák, M. (2010): Raman spectroscopic study of the uranyl sulphate mineral zippeite: low wavenumber and U–O stretching regions. – Anal. Bioanal. Chem. 397, 2700?$??KView article

Sejkora, J. – Pauliš, P. – Gramblička, R. – Dolníček, Z. – Ulmanová, J. – Pour, O. (2021): Měděná mineralizace z Horní Halže u Měděnce v Krušných horách (Česká republika). – Bull. Mineral. Petrolog. 29, 2, 351–368.View article

Urban M. – Crkal, J. (2021): Po stopách historie obce Měděnec a okolí. – 256 str. Obec Měděnec. Měděnec.