Your quarter was likely plated after being released into circulation and is only worth 0.25¢. The Philadelphia and Denver Mints only produce clad coinage.
It was probably plated. It was a big thing for the TV hucksters to create sets of plated SQ's (specimens that wouldn't grade high) using very, very thin layers of gold, silver and platinum which was so thin that it cost only pennies per coin. Then, they would sell these sets at huge premiums. The suckers that bought these sets would never recover their cost, and many just dumped them back into circulation when they realized they had been "taken". FYI, real silver SQ's were struck only at the San Francisco Mint.
Yeah I know about real silver being struck there but I've also heard of cases like with an Eisenhower silver dollar where a coin that was supposed to be clad was silver so I didn't know
You can always check the weight to be sure. Silver is 6.25 g (+/- 0.194g). Clad is 5.67g (+/- 0.227). If the quarter was silver it would've been hand fed into the striking chamber by an unscrupulous mint employee and I doubt it would have been released for circulation.