Black microcrystals of the extremely rare mineral IMA 2016-045 arsenmarcobaldiite on a white contrasting matrix. Analyzed specimen by SCXRD and EDS by C.Biagoni and S.Magnanelli. Part of the holotype specimen. All the very few known specimens come from a small block of rock found in an old dump between Arsiccio and Pollone mines. From: Verzalla, Sant'Anna di Stazzema, Tuscany, Italy. — Photo: David Hospital · CC BY-SA 4.0
Arsenmarcobaldiite
Arsenmarcobaldiite is an IMA-recognized mineral species in the sulfosalt class, with the chemical formula Pb₁₂(As₃.₂Sb₂.₈)Σ₆S₂₁.
It crystallizes in the triclinic crystal system (space group P-1). It is a member of the Geocronite structural group.
Key properties: Mohs hardness 3; specific gravity 6.44; Black streak; Metallic luster.
IMA symbol Amcb, IMA status: approved, named in 2016.
Found in hydrothermal quartz veins cutting schist.
It is found associated with Pyrite, sphalerite, quartz, baryte.
Indicates its essential arsenic and isotypic relationship with marcobaldiite.