Fraipontite Locality: Lavrion (Laurion; Laurium) District, Attikí (Attica; Attika) Prefecture, Greece ( Locality at mindat.org ) Size: thumbnail, 1.4 x 1.0 x 0.9 cm Fraipontite An old specimen in a micromount box which hosts several rich pockets of pearly white, sub-mm fraipontite crystals associated with green smithsonite. This is a rare zinc aluminosilicate species. Ex. John White Collection. — Photo: Robert M. Lavinsky · CC BY-SA 3.0
Fraipontite
A zinc-aluminium silicate of the kaolinite-serpentine group formed when zinc deposits oxidize.
Intro adapted from Wikipedia (CC BY-SA).
Fraipontite is an IMA-recognized mineral species in the silicate class, with the chemical formula (Zn,Al)₃(Si,Al)₂O₅(OH)₄.
It crystallizes in the monoclinic crystal system. It is a member of the Serpentine, Clay structural group.
Key properties: Mohs hardness 3.5–4; specific gravity 3.08–3.1; White to pale green streak; Silky luster; optically biaxial.
IMA symbol Fpt, grandfathered status — known before the IMA’s founding, named in 1927.
Found in oxidized zinc-bearing mineral deposits.
It is found associated with Smithsonite (Vieille-Montagne, Belgium); gebhardite, willemite, cerussite (Tsumeb, Namibia); sauconite (Silver Bill mine, Arizona, USA).
The mineral was named to honor Julien Jean Joseph Fraipont (1857–1910), and Charles Fraipont, of Liµege, Belgium, both geologists and paleontologists.