A Common 15c Marie-Adélaïde Cover? Perhaps not - take a close look at the stamp!

Luxembourg-Ville,

31 Mar 1921

to

Bettborn,

1 Apr 1921

Domestic 20g letter rate  = 15c

(12 Apr 1920—1 Apr 1921)

A nice rate cover, but look closer!

15c Marie-Adélaïde with

Caisse d'Epargne 

Luxembourg 

'star' perfin

(bottom center) 

Antunes and Basien, writing in Luxemburg Perfins (August 2015), state that the Caisse d'Epargne perfin was used from 1905 to 1928.  

Although this perfin is not particularly uncommon, uses on cover are scarce.