Civil War Mintzer Backmarked Pennsylvania National Guard Coat Button

Non dug Civil War Pennsylvania National Guard coat button. The front has centered Old English initials N. G. and an uncleaned patina. The reverse has a c.1860 depressed W. G. MINTZER. * PHILD. *, between two rings of dots, backmark. The shank is straight. This button measures 23 mm's in size. $150