Dark orange crystals of the extremely rare mineral scordariite (IMA 2019-010). From: Monte Arsiccio Mine, Apuan Alps, Tuscany, Italy. — Photo: David Hospital · CC BY-SA 4.0
Scordariite
Scordariite is an IMA-recognized mineral species in the sulfate class, with the chemical formula K₈(Fe³⁺₀.₆₇ ₀.₃₃)[Fe³⁺₃O(SO₄)₆(H₂O)₃]₂(H₂O)₁₁.
It crystallizes in the hexagonal crystal system (space group R-3). It is a member of the Metavoltine structural group.
Key properties: Mohs hardness 2–2.5; specific gravity 2.432; Yellowish streak; Vitreous luster; optically uniaxial.
IMA symbol Sda, IMA status: approved, named in 2019.
From the weathering of a pyrite + baryte + iron oxide (magnetite, hematite, “limonite”) deposit.
It is found associated with Giacovazzoite, krausite, gypsum, jarosite, alum-(K), magnanelliite.
The mineral was named to honor Fernando Scordari (b. 1944), retired Professor of Mineralogy, University of Bari, Italy.