Cubanite , Maucherite , Valleriite Locality: Mackinaw Mine (Weden Creek Mine), Monte Cristo , Monte Cristo District, Snohomish County , Washington , USA ( Locality at mindat.org ) Size: 12.6 x 9.2 x 5.1 cm. A hefty ore specimen, with probably tons of material stuck inside it as well as what you see on the outside, judging by the look of it. I think the cubanite (and associated more rare species) fills thin fracture seams within. On the exposed main face, there are dozens of thin, flat-lying cubanite crystals to 7mm in size. Apparently this specimen was exchanged to the Academy by the Smithsonian. Ex. Philadelphia Academy of Sciences and Smithsonian Institution Collections. — Photo: Robert M. Lavinsky · CC BY-SA 3.0
Valleriite
An uncommon bronze-yellow iron-copper hydroxysulfide forming soft nodules and crusts in ultramafic rocks.
Intro adapted from Wikipedia (CC BY-SA).
Valleriite is an IMA-recognized mineral species in the oxides & hydroxide class, with the chemical formula 2[(Fe,Cu)S]·1.53[(Mg,Al)(OH)₂].
It crystallizes in the hexagonal crystal system (space group R-3m). It is a member of the Valleriite structural group.
Key properties: Mohs hardness 1; specific gravity 3.14; Metallic to submetallic luster.
IMA symbol Val, grandfathered status — known before the IMA’s founding, named in 1870.
An alteration product of chalcopyrite in chromitites and dunites (Cyprus); in copper-bearing carbonatites, replacing magnetite (Phalaborwa, South Africa); in Cu–Ni sulfide-bearing serpentinized and uralized ultramafic rocks.
It is found associated with Chalcopyrite, cubanite, pyrrhotite, troilite, millerite, pentlandite, pyrite, marcasite, mackinawite, tochilinite, magnetite.
In honor of Johan Gottschalk Wallerius (Vallerius) (1709–1785), Swedish chemist and mineralogist.