Tarbuttite Locality: Skorpion Mine, Rosh Pinah , Lüderitz District, Karas Region , Namibia ( Locality at mindat.org ) Size: miniature, 4.1 x 2.8 x 1.6 cm Tarbuttite An elegantly formed specimen of large tarbuttite "sheaves" from this new find. In person, the color of the tarbuttite is a soft pastel green, very unusual and interesting! It is translucent when backlit. — Photo: Robert M. Lavinsky · CC BY-SA 3.0
Tarbuttite
A rare zinc phosphate discovered in 1907 at Broken Hill, Zambia.
Intro adapted from Wikipedia (CC BY-SA).
Tarbuttite is an IMA-recognized mineral species in the phosphate class, with the chemical formula Zn₂(PO₄)(OH).
It crystallizes in the triclinic crystal system (space group P-1). It is a member of the Tarbuttite structural group.
Key properties: Mohs hardness 3.5–4; specific gravity 4.19; White streak; Vitreous, pearly on cleavages luster; refractive index 1.693; optically biaxial.
IMA symbol Tbt, grandfathered status — known before the IMA’s founding, named in 1907.
Occurs as an uncommon secondary mineral in the oxidized zone of zinc-bearing deposits.
It is found associated with Hopeite, hemimorphite, smithsonite, parahopeite, hydrozincite, scholzite, cerussite, pyromorphite, descloizite, vanadinite, “limonite”.
The mineral was named to honor Percy Coventry Tarbutt, Director of the Broken Hill Exploration Company, who early provided material for characterization.