Opium_dollar
Trade-dollar locket
Locket made from two coins
A trade-dollar locket, also known as a box dollar or an opium dollar, is a type of locket created from two coins, typically trade dollars, that were hinged together to form a hidden compartment. As trade dollars circulated in Asia in the late 19th century, the lockets were popularly thought to be used to carry opium concealed in the secret compartment. An image could also be placed in the compartment of the coin making it a traditional locket.