Rules of attire during the lengthy period of mourning became more formalized during the Victorian period, then gradually faded from use by 1950. Those  bound by those cultural "rules" - particularly the mourning widow and (if the deceased was a child) the parents.

Though the mourning fan was not a requirement, in southern climates and particularly when a heavy crepe veil was worn, the fan became a health necessity.

For sale here is the mourning fan belonging to Mary Ellen Stanford, used when she became a widow in 1922 after losing her husband to a freak diving accident.  

It is black silk layered onto a heavy cardstock, with a silk tassle and brown and black wooden guard and stays. 

Length of fan = 25"

Diameter of fan, when opened = 25"

Length of a fan slat which is covered with fabric = 8"

Number of "blades" or slats: 8

Length of Tassle = 14"

CONDITION:  One section of the fan tore while taking photos for this listing. (See photos ). Can be easily repaired, if desired, with black fabric tape. Decorative black thread once woven decoratively through one end of the fan has come off and hangs free. The tassle is tousled and slightly knotted. Other than the one torn section, fan slats and the guard are in very good condition!