Celtic Gaul, The Sequani, Potin "Big Head" Unit.  

Obv: Stylized head left with thick features and helmet 
Rev: horse left with long tail.

Reference: DeLaTour N° 5368 (variety). 4,75gm; diameter around 20mm.
It is also a coin discovered in Jura. East of France.

Contributed by an amateur collector, May, 2004.