which quarters are pure silver

[HazelDella]

The provided context is insufficient to fully answer the question. Based on general numismatic knowledge, no United States quarters intended for general circulation were ever minted from pure silver.

Historically, circulating quarters were made from a durable silver alloy. Quarters minted in 1964 and earlier are composed of 90% silver and 10% copper. This composition applies to several series of quarters, including the Washington quarters (1932-1964), the Standing Liberty quarters (1916-1930), and the Barber quarters (1892-1916).

While circulating quarters were never pure silver, the U.S. Mint does produce modern quarters with a high silver content for collectors. These are special numismatic products, such as those found in annual silver proof sets, which are struck in .999 fine silver. These coins are not intended for general circulation. Therefore, to find a "pure silver" quarter, one would need to look at modern collectible issues rather than historical currency.