It is a salt of the ferric ion and oxalic acid.

Usually ferric ions are surrounded by six ligands arranged in octahedron.

Most iron-containing proteins contain ferric ions, at least transiently.

Results of the optical studies show that both minerals have ferrous and ferric ions (Chandrasekhar, 2003).

The first step of the catalytic cycle involves reduction of ferric ion to ferrous:

It binds ferric ions using six oxygens from three catechol groups, giving an overall charge of 3.

It forms a bright red complex with ferric ions.

Esculetin combines with ferric ions to produce a black complex.

The formation of the red-brown complex has long been used as a test for ferric ions.

The second step requires the entrance of ferric ions into the newly formed vesicles from the external environment.