Melonite , Calaverite Locality: Cresson Mine, Eclipse Gulch, Cripple Creek District, Teller County , Colorado , USA ( Locality at mindat.org ) Size: 1.3 x 0.9 x 0.4 cm. Melonite is an uncommon nickel telluride. This fine thumbnail from the Cresson Mine at Cripple Creek features at rich plate of melonite pseudomorphing calaverite (gold telluride) crystals and is very nicely accented by a small rosette of quartz crystals. The melonite rests on a thin crust of tiny quartz crystals. Highly representative of the species and historic locale. Probably very old material, too. — Photo: Robert M. Lavinsky · CC BY-SA 3.0
Melonite
Nickel telluride — an opaque white-to-reddish metallic mineral described in 1866 from California's Melones mine.
Intro adapted from Wikipedia (CC BY-SA).
Melonite is an IMA-recognized mineral species in the sulfide class, with the chemical formula NiTe₂.
It crystallizes in the hexagonal crystal system (space group P-3m1). It is a member of the Melonite structural group.
Key properties: Mohs hardness 1–1.5; specific gravity 7.72; Dark gray streak; Metallic luster.
IMA symbol Mlt, grandfathered status — known before the IMA’s founding, named in 1868.
With other tellurium minerals in the late stages of hydrothermal veins formed at medium to low temperatures. Also in high-temperature Ni–Cu–PGE magmatic sulfide deposits.
It is found associated with Altaite, petzite, hessite, calaverite, coloradoite, krennerite, tellurobismuthite, montbrayite, gold, pyrite, chalcopyrite, pentlandite, pyrrhotite.
The name refers to the Melones mine in California, USA, where it was discovered.