“Luxembourgite in association with clausthalite (bright), partially altered by goethite (grey). Reflected light digital image, width of photo 0.5 mm. Luxembourgite, AgCuPbBi4Se8, has been recently approved by the IMA-CNMNC (Philippo et al. 2019).
Note that El Dragón also contains abundant grains representing solid solutions between watkinsonite and luxembourgite. Noteworthy, luxembourgite from El Dragón is chemically closer to ideal composition than is the type material (cf. Grundmann & Förster 2017, their Table 3; see also Paar et al. 2012).
Also, a third locality for luxembourgite must be added, namely Schlema-Alberoda in the Western Erzgebirge, Germany. Watkinsonite analyzes in Förster et al. 2005 (Table 1) show that luxembourgite is also detected there.
Förster, H.-J., Rhede, D. and TISCHENDORF, G. (2005) Mineralogy of the Niederschlema–Alberoda U–Se-polymetallic deposit, Erzgebirge, Germany. Watkinsonite, nevskite, bohdanowiczite and other bismuth minerals. – Canad. Mineral., vol. 43, No. 3, p. 899–908.
Förster, H.-J., Bindi, L., & Stanley, C.J. (2016a) Grundmannite, CuBiSe2, the Se-analogue of emplectite: A new mineral from the El Dragón mine, Potosí, Bolivia. European Journal of Mineralogy 28, 467–477.
Grundmann, G. & Förster, H.-J. (2017) Origin of the El Dragón selenium mineralization, Quijarro province, Potosí, Bolivia. Minerals 7, No. 68.
Paar, W.H., Cooper, M.A., Moёlo, Y., Stanley, C.J., Putz, H., Topa, D., Roberts, A.C., Stirling, J., Raith, J.G., & Rowe, R. (2012) Eldragόnite, Cu6BiSe4(Se)2, a new mineral species from the El Dragόn mine, Potosí, Bolivia, and its crystal structure. Canadian Mineralogist 50, 281−294.
Philippo, S., Hatert, F., Bruni, Y. & Vignola, P. (2019) Luxembourgite, IMA 2018-154. CNMNC Newsletter No. 49, June 2019, page xxx; Mineralogical Magazine 83, 323–328.
G. Grundmann collection and photo.
Dr. Günter Grundmann - 11th September 2019