Goodyear's 1851 Hard Rubber Eagle Berdan Sharpshooter's Coat Button

Fine non dug coat size Goodyear's 1851 hard rubber eagle button. These hard rubber buttons were worn by Berdan's Sharpshooter's. The sun did not reflect off these buttons the way it did off brass ones. The front has a spread wing eagle and the reverse has a raised N. R. Co. GOODYEAR'S P=T 1851 backmark. The brass shank is straight. Measures 20 mm's in diameter. $275