Formula: Mn2+9(AsO4)2(AsO3)(OH)9.2H2O
Compound arsenate,
hematolite group,
manganese-bearing mineral
Crystal System: Orthorhombic
Specific gravity: 3.57 to 3.79 measured, 3.56 calculated
Hardness: 4½
Colour: Colourless (crystal centres), red to brown (exteriors), blackish; colourless to pale brown or reddish in transmitted light.
Solubility: Readily soluble in acids. Oxidises readily upon exposure to air
(Mindat)
Environments:
Metamorphic environments
Hydrothermal environments
Synadelphite is a rare low-temperature hydrothermal mineral occurring in metamorphosed deposits.
At Långban, Värmland, Sweden, synadelphite is associated with manganoan biotite,
allactite and hausmannite
(HOM).
At the type locality, the Moss mine, Värmland, Sweden, synadelphite cuts
hausmannite
ores in dolomitic marble,
associated with
pyrochroite, manganite,
jacobsite, allactite and
calcite
(HOM, Webmin)
At Sterling Hill, New Jersey, USA, synadelphite is associated with kraisslite
and allactite
(HOM).
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