It depends on what its date is and what country issued it. The two largest users of the 25¢ denomination are the US and Canada:
US1965 and later : none; the coins are made of copper-nickel1873-1964 : 5.625 gm
Canadamid 1968 and later : none; the coins are either nickel or nickel-plated steelmid 1967-mid 1968: 2.525 gm
1920-mid 1967 : 4.664 gm
1908-1919 : 5.384 gm
A 90% US silver quarter contains .18084oz of pure silver, or 5.12672 grams. All quaters before 1965 had this 90% composition.
The 1964 Washington Quarter has .18084oz of pure silver.
It is 90% silver and 10% copper.
$3.00
$50
If you mean a 1966 American quarter, then none.
Currently none.
$10
Pre-1965 silver quarters are 90% silver with a total weight of 6.25 grams, which is then 5.625 grams of silver per quarter.
The Actual Silver Weight (ASW) is .18084oz of pure silver.
The silver value is about 5-6 dollars.
The actual amount of pure silver is .18084 of an ounce.
1964 was the last year for silver quarters.