Watch List notes:

WESTERN ASIA MINOR, Uncertain. Late 6th-early 5th centuries BC. AR Obol(?) (8mm, 0.71 g). Archaic head (of Apollo?) left / Incuse square. Unpublished in the standard references. Deep iridescent tone, granular surfaces. Good VF. Beautiful portrait.

From the J. de Wilde Collection. Ex Herbert Cahn Collection (Numismatica Genevensis SA 7, 27 November 2012), lot 103 (part of).

A series of early coinage at Kolophon has a type similar to this issue (see below), but the style and weight of this piece suggest it is unrelated.