Ca4Al4(SO4)F2(OH)16·2H2O IMA 2018-057
The mineral is named in honor of the Dutch collector of Eifel minerals Fred Kruijen. In 2008 Fred found great specimen of blue Jeremejevite crystals in Wannenköpfe location. Unfortunatly this found location expired.
Kruijenite was found in a calcic xenolith of Feuerberg volcano near Daun, Rhineland-Palatinate, Germany. It's parageneticed with fluorite, aragonite, cuspidine, magnesioferrite, hematite, sharyginite, harmunite, and an insufficiently investigated hydrous Ca-Mg-Al silicate. Kruijenite occurs as pale greenish-yellow to colourless long prismatic tetragonal crystals up to 0.1 mm × 1 mm in cavities typically combined in radiating or random aggregates. For more details see these pictures im Mineralienwelt 04/2019.
Nikita V. Chukanov, Natalia V. Zubkova, Günter Blass, Igor V. Pekov, Dmitry A. Varlamov, Dmitriy I. Belakovskiy, Dmitry A. Ksenofontov, Sergey N. Britvin, Dmitry Yu. Pushcharovsky: Kruijenite, Ca4Al4(SO4)F2(OH)16•2H2O, a new mineral with microporous structure from the Eifel paleovolcanic region, Germany. Mineralogy and Petrology Vol. 113, Issue 2 (2019) S. 229–236.
Chukanov, N.V., Zubkova, N.V., Blass, G., Pekov, I.V., Varlamov, D.A., Belakovskiy, D.I., Ksenofontov, D.A., Britvin, S.N. and Pushcharovsky, D.Y. (2018) Kruijenite, IMA 2018-057. CNMNC Newsletter No. 45, October 2018, page xxx; Mineralogical Magazine, 82, xxx-xxx.