What is "maghemite"

n. (context mineralogy English) A magnetic mineral with a grey blue, white, or brown shade.

Maghemite (FeO, γ-FeO) is a member of the family of iron oxides. It has the same spinel ferrite structure as magnetite and is also ferrimagnetic.

Maghemite can be considered as an Fe(II)-deficient magnetite with formula $\left(\ce{Fe^{III}8}\right)_A\left[\ce{Fe^{III}_{40/3}\square_{8/3}}\right]_B\ce{O32}$ where ▫ represents a vacancy, A indicates tetrahedral and B octahedral positioning.