321 Florentina is an S-type (stony) main belt asteroid with a diameter of 28 km.

This asteroid is a dynamic member of the Koronis family.

[1] Photometric data collected during the asteroid opposition of 2011 was used to construct a light curve that displayed a rotation period of 2.870±0.001 h. This is consistent with previous rotation estimates.

[2] A group of astronomers, including Lucy d'Escoffier Crespo da Silva, contributed data toward the discovery of spin-vector alignments in the Koronis family, which includes (321) Florentina.

The collaborative work resulted in the creation of 61 new individual rotation lightcurves to augment previous published observations.