Iron-nickel phase in pallasite meteorites
First, a correction. A solid solution is between different compositions in the same phase. For example, olivine is a solid solution of forsterite (Mg2SiO4) and fayalite (Fe2SiO4).
There are two common iron–nickel alloys found in meteorites (pallasites and others): kamacite and taenite. They are commonly intergrown into lamallae called &quot;Widmanstätten pattern&quot;. It looks like this:

Kamacite has up to about 10% nickel, whereas taenite can get up to ~60% nickel, but commonly found up to 30%.
Kamacite has the space group Im3m, making it hexoctahedral body-centered. Taenite has the space group Fm3m, making it hexoctahedral face-centered.