Nickel is primarily found in sulfide ores. These ores are rocks that contain sulfide minerals, which are minerals composed of sulfur and a metal.

Here are some common sulfide ores where nickel is found:

* Pentlandite: A sulfide mineral containing nickel and iron. This is the most common nickel ore.

* Pyrrhotite: A sulfide mineral containing iron and a small amount of nickel.

* Millerite: A sulfide mineral containing nickel.

* Chalcopyrite: A sulfide mineral containing copper and iron, often containing traces of nickel.

Nickel can also be found in lateritic ores, which are formed by weathering and leaching of other rocks. These ores contain nickel in the form of oxides and hydroxides.

It's important to note that the specific rock type where nickel is found can vary depending on the geological location and the specific ore deposit.