minette

noun2

1. •
   A mineral deposit consisting of iron ore of sedimentary origin, found in the south of Luxembourg and in Lorraine.

   • The minettes of Buell Mountain are felsic, and many contain ground-mass quartz. — 1977
2. •
   (old-fashioned) The smallest of regular sizes of portrait photographs.

   • The title page bears a minette portrait of the Duke being crowned by the hand of an ideal figure of Chicago, and below are the coat-of-arms and motto of the Duke's house. — 1893