The levels of gold impurity in most silver coins minted more than 100-200 years ago appear to be an indication of the levels occurring in the original silver sources. Thus, it is often possible to group coins according to their gold: silver content ratios and to suggest possible geographic origins of the silver. During the past six years over 8000 coins and metallic art objects were analyzed using samples in the form of metal streaks on etched quartz tubing. Summarized here are analytical data for Sasanian (Persia: 224-650 AD) coins and silver art objects as well as Umayyad (Persia: 661-750 AD) and Byzantine coins. Data are also presented on the identification of modern forgeries of ancient and medieval coins and Sasanian art objects, the use of Mexican and South American (Potosi) silver in Spanish and other European coinage and its relationship to the price revolution of sixteenth-century Europe, and the questionable honesty in the minting of Zapatista Revolutionary Mexican coinage of 1914-1915.