Greenish globular aggregates of the rare mineral symplesite from Czech Republic (Krupka, Krušné Hory, Ústí nad Labem Region, Czech Republic). Ex Vandenbroucke Museum collection from Waregem, Belgium. — Photo: David Hospital · CC BY-SA 4.0
Symplesite
Symplesite is an IMA-recognized mineral species in the arsenate class, with the chemical formula Fe²⁺₃(AsO₄)₂·8H₂O.
It crystallizes in the triclinic crystal system. It is a member of the Symplesite structural group.
Key properties: Mohs hardness 2.5; specific gravity 2.96–3.01; Pale bluish streak; Vitreous to oily, pearly on cleavages luster; optically biaxial.
IMA symbol Sym, grandfathered status — known before the IMA’s founding, named in 1837.
A rare secondary mineral found in the oxidized zone of some arsenic-rich hydrothermal mineral deposits.
It is found associated with Pharmacosiderite, scorodite, erythrite, roselite, annabergite, parasymplesite, “limonite”.
Its name comes from the Greek for with and to be associated, in allusion to the other rare arsenates accompanying it in the original occurrence.