Oyonite, Ag3Mn2Pb4Sb7As4S24, a New Member of the Lillianite Homologous Series from the Uchucchacua Base-Metal Deposit, Oyon District, Peru

Abstract

Abstract:The new mineral species oyonite, ideally Ag 3 Mn 2 Pb 4 Sb 7 As 4 S 24 , has been discovered in the Uchucchacua base-metal deposit, Oyon district, Catajambo, Lima Department, Peru, as very rare black metallic subhedral to anhedral crystals, up to 100 µm in length, associated with orpiment, tennantite/tetrahedrite, menchettiite, and other unnamed minerals of the system Pb-Ag-Sb-Mn-As-S, in calcite matrix. Its Vickers hardness (VHN 100 ) is 137 kg/mm 2 (range 132-147). In reflected light, oyonite is weakly to moderately bireflectant and weakly pleochroic from dark grey to a dark green. (11) • , V = 2004.1 (4) Å 3 , Z = 2. The crystal structure was refined to a final R 1 = 0.032 for 6272 independent reflections. Oyonite belongs to the Sb-rich members of the andorite homeotypic sub-series within the lillianite homologous series. The name oyonite is after the Oyon district, Lima Department, Peru, the district where the type locality (Uchucchacua mine) is located.

Agmantinite, Ag2MnSnS4, a new mineral with a wurtzite derivative structure from the Uchucchacua polymetallic deposit, Lima Department, Peru

“…This zone is characterised by the occurrence of alabandite and silver minerals. Uchucchacua is the type locality for six Mn-bearing sulfides/sulfosalts: uchucchacuaite, AgPb 3 MnSb 5 S 12 (Moëlo et al , 1984); benavidesite, Pb 4 MnSb 6 S 14 (Oudin et al , 1982); manganoquadratite, AgMnAsS 3 (Bonazzi et al , 2012); menchettiite, AgPb 2.40 Mn 1.60 Sb 3 As 2 S 12 (Bindi et al , 2012); oyonite, Ag 3 Mn 2 Pb 4 Sb 7 As 4 S 24 (Bindi et al , 2018); agmantinite, Ag 2 MnSnS 4 (this work); and including keutschite, Cu 2 AgAsS 4 (Topa et al , 2014) and spryite, Ag 8 (As 3+ , As 5+ )S 6 (Bindi et al , 2017). It is the type locality of seven silver minerals, as well as being the type locality of hyršlite, Pb 8 As 10 Sb 6 S 32 (Keutsch et al ., 2017).…”

Editorial for Special Issue “New Mineral Species and Their Crystal Structures”

“…Ore minerals in this Special Issue are represented by gold amalgam aurihydrargyrumite, Au 6 Hg 5 , found on gold particles in the Iyoki deposit at Shikoku Island, Japan [14]; oyonite, Ag 3 Mn 2 Pb 4 Sb 7 As 4 S 24 , a new sulphosalt of the lillianite homologous series from the Uchucchacua deposit in Oyon district, Peru [15]; and cerromojonite, CuPbBiSe 3 , a new selenide of the bournonite group from the El Dragón mine in Potosí, Bolivia [16].…”