Pieczkaite
Pieczkaite is an IMA-recognized mineral species in the phosphate class, with the chemical formula Mn₅(PO₄)₃Cl.
It crystallizes in the hexagonal crystal system (space group P6_3/m). It is a member of the Apatite structural group.
Key properties: Mohs hardness 4–5; specific gravity 3.783; Grayish white streak; optically uniaxial.
IMA symbol Pzk, IMA status: approved, named in 2014.
Occurs as small patches and narrow veins in apatite and (Mn, Cl)-bearing apatite in phosphate pods in the interior wall zone of the quartz core of a granitic pegmatite.
It is found associated with Fluorapatite, manitobaite, eosphorite, triploidite, quartz.
The mineral was named to honor Adam Pieczka (b. 1957), Assistant Professor, Department of Mineralogy, Petrography, and Geochemistry, Faculty of Geology, Geophysics, and Environmental Protection.