NNP

Inhomogeneity.  An alloy whose ingredients are not thoroughly mixed, the blending of metals is not complete and the resulting alloy is not constant – homogeneous – throughout. Inhomogeneity is an anomaly of melting without proper agitation prior to ingot casting. The metals were not allowed to blend to form a homogeneous mass. In struck coins inhomogeneity is evident as streaks of off color – from pale pink to light gray or brown for example – on the surface of such coins. This was quite common in U.S. wartime nickels of high silver content (1942-45); the color of streaks in the unmixed alloy of these coins ranged in color from to red (from the copper) to silvery white (from the silver or manganese), or sometimes both in the same piece! It differs from a bullion blunder, which is an error of amount of metal added during formulation.  See ingot (2).

References:                                                                                                                                 

C60 {1970} Breen [Minting Process] p 49.

excerpted with permission from

An Encyclopedia of Coin and Medal Technology

For Artists, Makers, Collectors and Curators

COMPILED AND WRITTEN BY D. WAYNE JOHNSON

Roger W. Burdette, Editor