Silver bullion and U.S. Silver coinage When coins had intrinsic value
On September 9th, 1963 the price of pure silver hit $1.293 per ounce. That was a new record for the 20th century and it caused a problem for the U.S. Treasury Department: coins in circulation were now worth their face value. That is, counting the cost of refining to pure silver (coinage was 90% silver at that time), a silver dollar in the palm of your hand was actually worth one dollar for the value of the silver in it.
There were few if any silver dollars actually in circulation by 1963, but dimes, quarters and half dollars were and they also contained 90% silver. Silver dollars did turn up now and then — they were the chips used at casinos and were popular as Christmas presents.
Ten silver dimes would have weighed just a tiny bit less than one silver dollar, so even the minor coins were in danger of being worth more than their face value.