Lammerite , Lemanskiite Locality: El Guanaco Mine, Guanaco (Huanaco) , Santa Catalina , Antofagasta Province , Antofagasta Region , Chile ( Locality at mindat.org ) Size: 5.0 x 4.5 x 4.0 cm. A VERY RICH and excellent combination specimen of the RARE and an uncommon copper arsenates from the El Guanaco Mine of Chile. Rare, dark green, microcrystals of lammerite are nicely accented with turquoise-blue sprays of uncommon lamanskiite on a quartz-rich matrix. The El Guanaco Mine is the Type Locality for lemanskiite. — Photo: Robert M. Lavinsky · CC BY-SA 3.0
Lammerite
A rare blue-green anhydrous copper arsenate-phosphate forming monoclinic crystals.
Intro adapted from Wikipedia (CC BY-SA).
Lammerite is an IMA-recognized mineral species in the arsenate class, with the chemical formula Cu₃(AsO₄)₂.
It crystallizes in the monoclinic crystal system (space group P2_1/a).
Key properties: Mohs hardness 3.5–4; specific gravity 4.9–5.18; Pale green streak; Adamantine, vitreous on cleavage surfaces luster; optically biaxial.
IMA symbol Lmr, IMA status: approved, named in 1980.
On an old mineral specimen (Laurani, Bolivia); in an oxidized zone in a dolostone-hosted hydrothermal polymetallic ore deposit (Tsumeb, Namibia); in volcanic sublimates (Tolbachik fissure volcano, Russia).
It is found associated with Olivenite (Laurani, Bolivia); chalcanthite, anhydrite, leightonite (Tsumeb, Namibia); euchlorine, melanothallite, dolerophanite, chalcocyanite, leningradite.
The mineral was named to honor Franz Lammer, mineral collector of Leoben, Austria, who provided the first specimen.