Menchettiite

menchettiite

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Formula: Pb5Mn3Ag2Sb6As4S24
Sulphosalt, lillianite homologous series group
Crystal System: Monoclinic
Specific gravity: 5.146 calculated for the empirical formula
Hardness: 2½ to 3
Streak: Black
Colour: Black
Environments

Metamorphic environments
Hydrothermal environments

Menchettiite is a relatively new mineral, approved in 2011 and to date (February 2024) reported only from the type locality.

Localities

At the type locality, the Uchucchacua Mine, Oyón District, Oyón Province, Lima, Peru, menchettiite occurs as black, anhedral to subhedral grains up to 200 µm across, closely associated with orpiment, tennantite-tetrahedrite, other unnamed minerals of the system Pb-Ag-Sb-Mn-As-S, and calcite. Menchettiite is opaque with a metallic lustre and a black streak. (AM 97.2.440-446).
It occurs in a polymetallic (Ag-Mn-Pb-Zn) vein, replacement, and contact metamorphic mineral district (HOM).
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