Lady of the Court of Napoléon I, Attributed to Jean-Baptiste Isabey
In the Metropolitan Museum of Art, roughly 10×7 in (25×18 cm).
Though graphite pencils largely took the place of chalk and crayon in the late 19th century, this beautiful portrait drawing — done at the turn of the 19th century and attributed to court painter Jean-Baptiste Isabey — shows some of the delicacy and surface quality that can be achieved with crayon.
Elements of the drawing are highlighted with what is likely white gouache.
Link: Lady of the Court of Napoléon I, Met Museum