I saw this article about an ancient hoard of silver objects that were actually only silvered, like LRB's.
"The Beit Shean hoard of silver, which weighs about 5.5 ounces (157 grams), contained ingots of only 40% silver, which had been alloyed with copper and other cheap metals. The ingots had an enriched silver surface but a copper-rich core that may have been achieved by slowly cooling the ingot after it was melted and poured out." (picture below)
"The Megiddo hoard, which weighed 3.4 ounces (98 grams) had an even lower amount of silver — around 20%. But the debasement had been disguised by the addition of the elemental metal arsenic, which gives a silvery shine to copper."
https://www.livescience.com/ancient-egyptian-hoard-counterfeit-dirty-money.html
