Electrum coins [ source ] First proposed by economist Alfred Marshall in the late 19th century as an alternative metallic standard to the gold, silver and bimetallic standards, symmetallism was widely debated at the time but never adopted. Marshall's idea amounted to fusing together fixed quantities of silver and gold in the same coin rather than striking separate gold and/or silver coins. Symmetallism is actually one of the world's oldest monetary standards. In the seventh century B.C., the kingdom of Lydia struck the first coins out of electrum , a naturally occurring mix of gold and silver. Electrum coins are captured in the above photo. While symmetallism is an archaic concept, it has at least some relevance to today's world. Modern currencies that are pegged to the dollar (like the Hong Kong dollar) act very much like currencies on a gold standard, the dollar filling in for the role of gold. A shift from a dollar peg to one involving a basket of other currencies amoun...