Symplesite

symplesite

pharmacosiderite

parasymplesite

vivianite

Formula: Fe2+3(AsO4)2.8H2O

Hydrated normal arsenate, vivianite group (Dana), may be intergrown with its paramorph, parasymplesite (Mindat).
Crystal System: Triclinic
Specific gravity: 2.96 to 3.01 measured, 3.02 calculated
Hardness: 2½
Streak: White, bluish white
Colour: Light green, greenish black, light blue, indigo blue
Solubility: Soluble in acids. Turns reddish brown in strong KOH solution or in 30% H2O2 (Mindat).
Environments

Hydrothermal environments

Symplesite is a rare secondary arsenate in the oxidised zone of some arsenic-rich hydrothermal mineral deposits, associated with pharmacosiderite, scorodite, erythrite, roselite, annabergite, parasymplesite and limonite (HOM, Mindat).

At the type locality, Tännig, Bad Lobenstein, Thuringia, Germany, symplesite occurs in the oxidised zone of arsenic-bearing hydrothermal deposits, associated with scorodite, roselite, pharmacosiderite, parasymplesite, erythrite and annabergite (Mindat).

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