Merelaniite
A molybdenum-bearing member of the cylindrite group — so far found only in Tanzania's Merelani tanzanite deposit.
Intro adapted from Wikipedia (CC BY-SA).
Merelaniite is an IMA-recognized mineral species in the sulfosalt class, with the chemical formula Pb₄Mo₄VSbS₁₅.
It crystallizes in the triclinic crystal system (space group C1). It is a member of the Cylindrite structural group.
Key properties: specific gravity 4.895; Dark gray to black streak; Metallic luster.
IMA symbol Ml, IMA status: approved, named in 2016.
Found in crevices loosely attached to alabandite crystals, intimately in association with masses of loosely aggregated graphite crystals. In a region of granulite-facies metamorphism of organic-rich black-shales rich in vanadium.
It is found associated with Zoisite (variety tanzanite), prehnite, stilbite, chabazite, tremolite, diopside, quartz, calcite, graphite, alabandite, wurtzite.
The mineral was named to honor the local miners, past and present, living and working in the township of Merelani.