Hydrated vanadate, manganese-bearing mineral
Specific gravity: 3.21 to 3.22
The type locality is Fianel, Ausserferrera, Ferrera, Viamala Region, Grisons, Switzerland. The Fianel deposit is remarkable because of the variety of its ores. The orebody consists of:
(1) An iron oxide ore comprising hematite and quartz, with or without strontian baryte and fluorapatite.
(2) an iron silicate ore comprising aegirine with or without quartz and strontian baryte.
(3) a complex iron-manganese ore comprising quartz, braunite, jacobsite, hematite, rhodonite, tephroite, rhodochrosite, kutnohorite, calderite and spessartine, with or without fluorapatite, strontian baryte, barylite and medaite.
Medaite-rich ores occur as lenses inside the iron and manganese ores. The ores are crosscut by several generations of veinlets that contain quartz, rhodonite, kutnohorite, aegirine, parsettensite, palenzonaite, saneroite and pyrobelonite.
These veins are in turn crosscut by thin open fractures containing quartz, aegirine, limonite, and tiny orange-red crystals of fianelite. Medaite grew during the first crystallisation stage and fianelite represents the last generation of vanadate crystallisation (AM 81.1270-1276).
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