Nickel is silvery-white and takes on a high polish. Nickel corrosion is a bright lemon-green.
It is hard, malleable, ductile, slightly ferro-magnetic, and a fair conductor of heat and electricity. It is chiefly used in an alloy, for example with copper to form 'nickel silver'.
Electro-nickel plating is often used over lead and copper to provide a protective coating. Otherwise, the period house owner will come across it in nickel silver.
Some forms of nickel are potentially carcinogenic so limit your exposure to dust.
Nickel corrodes slowly over time. It can be cleaned gently with a metal polish.