Orange microcrystals of the very rare mineral Mn-As silicate arsemmedaite from the TL in Molinello mine (Molinello Mine, Ne, Graveglia Valley, Genova Province, Liguria, Italy). Ex. Erich Laskowski collection (USA). — Photo: David Hospital · CC BY 4.0
Arsenmedaite
Arsenmedaite is an IMA-recognized mineral species in the silicate class, with the chemical formula Mn²⁺₆As⁵⁺Si₅O₁₈(OH).
It crystallizes in the monoclinic crystal system (space group P2_1/n). It is a member of the Medaite structural group.
Key properties: specific gravity 3.772; White streak; Vitreous luster.
IMA symbol Amed, IMA status: approved, named in 2017.
A late-stage hydrothermal mineral in quartz veinlets that cut braunite ore bodies hosted by metacherts, which overlay a mafic-ultramafic ophiolitic sequence.
It is found associated with Calcian rhodochrosite, talc, braunite, quartz, calcite, As-rich medaite, ganophyllite.
Indicates the arsenic analogue of mediate.