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Formula: Mn2+2V2O7.2H2O
Hydrated vanadate,
manganese-bearing mineral
Crystal System: Monoclinic
Specific gravity: 3.21 measured, 3.217 calculated
Hardness: 3
Streak: Orange
Colour: Orange-red
Environments
Localities
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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