Jeankempite
A rare calcium arsenate mineral named for geochemist Jean Kemp.
Intro adapted from Wikipedia (CC BY-SA).
Jeankempite is an IMA-recognized mineral species in the arsenate class, with the chemical formula Ca₅(AsO₄)₂(AsO₃OH)₂(H₂O)₇.
It crystallizes in the triclinic crystal system (space group P-1).
Key properties: Mohs hardness 1.5; specific gravity 2.92; White streak; Waxy luster; optically biaxial.
IMA symbol Jkp, IMA status: approved, named in 2018.
Occurs as intergrowths with guérinite coating oxidized copper arsenides. Likely formed by a topotactic reaction during dehydration of preexisting guérinite and post-mining oxidation.
It is found associated with Guérinite, calcite, ankerite, rauenthalite, annabergite, lavendulan.
The mineral was named to honor Jean Petermann Kemp Zimmer (1917-2001), curator of the A. E. Seaman Mineral Museum in Houghton, Michigan, USA, from 1975 to 1986.