Kruijenite (Image width: 1.5 mm) Locality: Feuerberg, Hohenfels-Essingen, Gerolstein, Vulkaneifel, Rhineland-Palatinate, Germany Description: Kruijenite in typical yellow/greenish crystals. Kruijenite is accepted by IMA sept. 2018-057 — Photo: Fred Kruijen · CC BY-SA 3.0 nl
Kruijenite
Kruijenite is an IMA-recognized mineral species in the sulfate class, with the chemical formula Ca₄Al₄(SO₄)F₂(OH)₁₆·2H₂O.
It crystallizes in the tetragonal crystal system (space group P4/nnc).
Key properties: Mohs hardness 3; specific gravity 2.573; Vitreous luster; optically uniaxial.
IMA symbol Kje, IMA status: approved, named in 2018.
Found in fragments of altered calcic xenolith from tephra, the product of pyrometamorphic and hydrothermal alteration by magmatic volatiles.
It is found associated with Fluorite, calcite, aragonite, cuspidine, magnesioferrite, hematite, sharyginite, harmunite.
The mineral was named to honor Dutch collector of Eifel minerals Fred Kruijen (b. 1956).