Kamacite is a mineral. It is a naturally occurring alloy of iron and nickel, usually in the proportion of 90:10 to 95:5 although impurities such as cobalt or carbon may be present. It has a metallic lustre, is grey and has no clear cleavage although the structure is isometric-hexoctahedral. Its density is around 8 g/cm³ and its hardness is 4 on the Mohs scale. It is also sometimes called balkeneisen.

It was first named in 1861 from the Greek kamask (lath or beam). It is found in meteorites. Meteoric kamacite is found in bands in octahedrites or hexahedrites, these sometimes contains Neumann bands, evidence of impact, or Widmanstätten's patterns. It is difficult to distinguish visually from the similar meteor alloy taenite and the two can be found closely intermixed as plessite.

See also: list of minerals