White acicular crystals of the rare mineral khademite associated to yellow natrojarosite and minoritary pickeringite from Cerros Pintados (Iquique Province, Tarapacá Region, Chile), the type locality for pickeringite. Analyzed specimen. — Photo: David Hospital · CC BY-SA 4.0
Khademite
Khademite is an IMA-recognized mineral species in the sulfate class, with the chemical formula Al(SO₄)F·5H₂O.
It crystallizes in the orthorhombic crystal system (space group Pcab). It is a member of the Khademite structural group.
Key properties: specific gravity 1.925; optically biaxial.
IMA symbol Kdm, IMA status: approved, named in 1973.
Rarely formed in the oxidized zone of hydrothermal base-metal deposits.
It is found associated with Copiapite, amarantite, parabutlerite, butlerite, jarosite (Saghand, Iran); wilcoxite, lannonite, gypsum (Lone Pine mine, New Mexico, USA).
The mineral was named to honor Nasrollah Khadem (1910–), Director of the Geological Survey of Iran.