Colorless pearly crystal aggregates of the very rare mineral kulkeite from the TL in Algeria (El Mourdur Hill, Derrag, Tell Atlas, Aïn Defla Province, Algeria). The specimen is partially polished because it was analyzed. Ex Vandenbroucke Museum collection from Waregem, Belgium. — Photo: David Hospital · CC BY 4.0
Kulkeite
Kulkeite is an IMA-recognized mineral species in the silicate class, with the chemical formula Na₀.₃Mg₈Al(Si,Al)₈O₂₀(OH)₁₀.
It crystallizes in the monoclinic crystal system. It is a member of the Corrensite, Clay structural group.
Key properties: Mohs hardness 2; specific gravity 2.7; White streak; Pearly on the cleavage luster; optically biaxial.
IMA symbol Klk, IMA status: approved, named in 1980.
Found in dolostone, metamorphosed below 400 ± C, with evaporites.
It is found associated with Talc, chlorite, phlogopite, tourmaline.
The name refers to Dr. Holger Kulke, geologist of Essen, Germany, who provided the original specimen.