[{"from": "human", "value": "Provide a brief overview of this molecule. [O-1][S][=Branch1][C][=O][=Branch1][C][=O][O-1].[Ni+2]"}, {"from": "gpt", "value": "The molecule is a yellow-green crystalline solid. Nickel sulfate can also be obtained as a hexahydrate (NiSO4.6H2O (CAS: 10101-97-0) which is blue to emerald green, and as a heptahydrate (NiSO4.7H2O) (CAS: 10101-98-1) , which is green. Samples can contain variable quantities of water, depending on their previous exposure to moisture or conditions. All forms are mildly toxic and are carcinogenic. All are denser than water. The primary hazard is the threat to the environment. Immediate steps should be taken to limit its spread to the environment. Used to make other nickel compounds, in printing, and in dyeing of textiles."}]