American coin shops sell bags of ordinary circulated dimes and quarters priced by their silver content. The trade nickname is junk silver, and the term describes condition rather than quality.
The composition changed in a single year
United States dimes, quarters and half dollars minted before 1965 were struck in an alloy that is ninety parts silver and ten parts copper, giving them substantial metal content.
The composition was changed to a copper-nickel clad construction as silver's rising value made the coins worth more than their face value.
That sharp cutoff is what makes the category so easy to define. A date is enough to determine whether a coin contains silver.
Wear removed the collector premium
Coins that circulated for decades lost surface detail. Grading depends heavily on preservation, so heavily worn examples of common dates hold no premium over their metal.
Scarce dates and mint marks are pulled out of any accumulation by dealers before the rest is bagged, so what remains genuinely is common material.
The result is a product priced almost entirely on silver content, with the coin format serving as a convenient package rather than a collectible.
Face value became a unit of trade
Dealers quote these coins by total face value rather than by weight, because the silver content per dollar of face value is essentially constant across the denominations.
Circulation wear removes a small amount of metal, so the practical silver content of a worn bag is slightly below the theoretical figure, and pricing conventions account for this.
Quoting in face value also makes small transactions simple, since a handful of quarters converts to a metal quantity without weighing anything.
Divisibility explains much of the appeal
A dime contains a small fraction of an ounce, which makes the format far more divisible than any bar or one-ounce coin.
Buyers who value the ability to sell small quantities pay a premium for that divisibility, and it widens when retail demand for silver rises.
That premium is a market price for convenience and can compress again when demand cools, which is worth knowing before treating it as permanent.
Authentication is comparatively simple
These coins have known weights, diameters and sounds when struck, and their genuine specifications are published by the mint that produced them.
Counterfeits exist but face a difficult economic problem, since the value per coin is low relative to the effort required to fake one convincingly.
That combination of familiarity and low unit value is a large part of why American dealers keep the category in stock continuously.