|Other names|| nickelous oxide |
|Molar mass||74.69 g/mol|
|Appearance||green crystalline solid|
|Density and phase||6.67 g/cm3, solid|
|Solubility in water||negligible|
|EU classification||not listed|
| Except where noted otherwise, data are given for|
materials in their standard state (at 25 °C, 100 kPa)
Nickel(II) oxide is the chemical compound with the formula NiO. It is notable as being the only well characterised oxide of nickel although there have been many reports of others (nickel(III) oxide, Ni2O3, and nickel dioxide, NiO2).
The mineralogical form of NiO, bunsenite, is very rare. It was suspected for causing green colour of chrysoprase, but later it was rejected.